The electoral arithmetic behind ‘One Nation, One Election’
India has been debating ‘One Nation, One Election’ (ONOE/ ONOP: i.e., holding Lok Sabha and State Assembly elections at the same time) for a long time.
Most of the discussion has focused on operational benefits such as smoother administration, lower costs, fewer disruptions from the Model Code of Conduct, and questions about how it fits with India’s federal system.
For a party seeking a fourth consecutive term at the Centre, the upside for BJP in pure vote-share terms due to ONOP may be limited, while the downside could be dangerously high.
This article examines this hypothesis comprehensively, weighing arithmetic, history, political incentives, empirical patterns, and the feasibility of testing this hypothesis using simulation-based risk assessment.
The core hypothesis
Right now, elections for Parliament and state assemblies happen at different times. This has made it hard for Congress and strong regional parties to form lasting alliances.
If elections were held together, this barrier could fall. Parties could strike seat-sharing deals where regional parties focus mainly on Assembly seats (with less interest in Lok Sabha seats), and Congress focuses more on Lok Sabha (LS) seats (with less interest in Assembly seats).
This could minimize the mutual distrust and improve the transfer of votes between allies, and allow the combined opposition vote to challenge or even beat the BJP in several large states.
For a party like BJP that is aiming for a fourth consecutive term in power at the Centre, any gain in pure vote share due to simultaneous elections may be small, while the risk of a stronger, united opposition could be high.
This article looks at the idea from several angles: vote arithmetic, past examples, political incentives, real-world patterns, and whether the risks can be assessed through computer simulations.
How the opposition vote gets split
First-past-the-post system amplifies even small vote share gaps into large seat share gaps.
In many important states, the anti-BJP vote is divided between Congress and the main regional party/ parties.
Even when Congress gets only a modest or single-digit share of votes on its own, adding that to the regional party’s share can produce a total % that matches or beats BJP’s vote share in many seats in large states such as UP, Bihar, Maharashtra and West Bengal.
In the 2024 LS polls, the ‘SP – Congress’ combine performed strongly in UP, and the MVA alliance did well in Maharashtra.
Distrust between the parties, fights over who should lead the alliance, and the fact that state and national elections usually fall on different dates make lasting alliances difficult.
Party workers often struggle to transfer votes smoothly when the two elections are years apart, because they do not fully trust each other. Sacrificing a constituency for the alliance partner would mean sacrificing their persona; interest.
With simultaneous elections, parties would negotiate only once. Regional parties could keep most Assembly seats while Congress takes most LS seats.
This kind of deal better matches each party’s strengths and the expectations of their workers, since most constituencies would be allotted to the regional party/ parties and Congress, either for Assembly or LS.
After many years being out of power at the Centre (and sometimes in states), all the opposition parties may also be more willing to accept such compromises.
The result could be a better chance of alliances taking shape, better vote transfer and a higher chance of alliance governments both at the Centre and in several states.
For BJP, any gain in votes looks modest compared with the danger of facing a more united opposition, esp. when the party is already performing near the upper end of what national parties have historically achieved while trying to stay in power for long periods.
Historical Precedent: The MGR formula
A clear historical model exists.
In the mid-1980s (esp. around the 1984 elections), MGR’s AIADMK and Congress used what became known as the ‘MGR formula.’
AIADMK contested most Assembly seats (about two-thirds), while Congress got most LS seats (about two-thirds). Both sides gained: AIADMK kept power in Tamil Nadu, and Congress won a large number of parliamentary seats from the state.
Vote transfer worked well enough for both to benefit.
Similar uneven seat-sharing deals have happened in other states at other times. Exact numbers always depend on local realities: organisational strength, recent results, caste and community numbers, and leadership calculations.
The only obstacle to such an arrangement is the conduct of elections far apart in time, and the resultant mutual distrust between the national and regional parties.
The basic principle is: when partners mainly want power at different levels, a single simultaneous election makes it easier to divide seats cleanly and stick to the deal than two separate election calendars.
Why staggered elections make alliances harder
Different timing raises the cost of bargaining. Parties must negotiate seat-sharing twice, often under different power balances.
A regional party that has just won a state election may feel little need to give seats to Congress for the later LS election.
Conversely, a Congress that has done relatively well nationally may later demand more Assembly seats.
Party workers who worked hard for one election may refuse to transfer votes for the other if they feel the alliance terms are unfair or may not be honoured later.
INDI Alliance experiment itself showed both the possibility of national-level coordination for LS seats and how quickly parties returned to state-level rivalry once Assembly elections approached.
Distrust is the deepest problem.
A simultaneous calendar collapses two separate bargaining rounds into one and lines up the time horizons of state and national power. That can reduce friction even if it cannot remove the underlying competition for dominance within the opposition.
How simultaneous elections could alter bargaining dynamics
Under ONOP, a single negotiation can allocate both Assembly and LS seats according to each partner’s comparative advantage.
Regional parties secure the bulk of state seats and the prospect of forming or leading state governments.
Congress secures a larger share of LS seats and a clearer path to national influence.
Cadres’ interests can be accommodated within a coherent package rather than across two disconnected cycles.
The longer the opposition remains out of power at the Centre, the greater the incentive to accept such compromises.
Studies consistently show higher rates of straight-ticket voting and greater party salience when elections coincide.
One often-cited analysis found roughly a 75% chance that the same party or alliance wins both levels when polls are simultaneous; that probability falls when the contests are separated.
Academic work on synchronised elections in India has estimated a 15–20% increase in the likelihood that the same party wins across levels, partly because fewer people split their votes.
These coattail effects can amplify a well-coordinated opposition alliance; they can equally amplify a nationally stronger party if the opposition remains only partially unified.
Interestingly, this was one of the important reasons for the objection of the opposition parties to ONOP, while this could itself work to their advantage in the current evolving situation.
Major risk for BJP
For BJP, the electoral upside of ONOP, measured in vote-share terms, appears limited if the opposition consolidates effectively.
BJP is seeking extended continuity at the Centre. Historical performance of national parties seeking multiple consecutive terms suggests that it is not easy.
The non-electoral arguments, viz., governance continuity, reduced administrative disruption, and fiscal savings, are real, but they are different from party politics.
The downside risk is more pronounced.
A successful opposition consolidation under simultaneous rules could produce a sharper reversal than staggered contests.
Recovery opportunities that exist when state elections are spread across the cycle, which BJP is very good at, would be reduced.
The 2004 precedent is instructive. NDA, buoyed by recent state victories, strong growth numbers, opinion poll confidence, and the ‘India Shining’ campaign, called early elections from a position of perceived strength.
Vajpayee himself was reportedly reluctant.
The result was a loss of power.
Simultaneous elections would concentrate any such miscalculation into a single high-stakes moment.
Should BJP take the risk?
There is no objective answer independent of internal assessments.
Three factors matter most:
- Whether Congress and major regional parties agree amiably on seat-sharing and transfer most of each other’s votes mutually, under ONOP.
- Whether BJP’s organisational depth, resource advantages, and national wave, if any, will still deliver a working majority or strong vote share even against improved opposition coordination.
- Governance and administrative benefits, which will be a minor factor, if at all.
If the first probability is judged substantive, 2004 experience becomes a relevant caution.
If the first probability is judged low and the second high, the risk may be manageable.
Rational actors inside BJP can reach either conclusion.
The decision is political rather than purely arithmetic.
Why not test the possible outcomes by simulation?
In my opinion, a multi-scenario simulation is both feasible and useful. It won’t be perfect, but if the BJP can read the big picture from it, it will give them the answers they need
The essential components are:
- Baseline 2024 (or most recent) vote shares and seat outcomes in the major states.
- Variable parameters: without simultaneous elections vs. with them; vote-transfer efficiency (e.g., 60%, 75%, 90%); possible seat-sharing formulas; likely % of coattail effect (e.g., 0%, 5%, 10%, 15%); residual fragmentation of vote shares (of smaller parties not in any alliance, rebels, independents, and voters who won’t back allies of their preferred parties); voter turnouts; and national-wave scenarios (mild BJP advantage, neutral, mild opposition advantage).
- Outputs: projected seats for the NDA versus the opposition alliance in each large state; aggregate LS seat distributions; and sensitivity analysis showing which assumptions move the results most.
Monte Carlo methods can generate probability distributions of majority and minority government, or clear opposition victory under different combinations of assumptions.
Such an exercise will not predict the future with precision, but it can map the plausible upside and downside ranges and clarify the conditions under which opposition consolidation becomes electorally dangerous for BJP.
Counter-arguments and limitations
Several important caveats apply.
Alliance friction is driven by mutual distrust and shifting relative strength, regardless of the electoral calendar alone. But it is difficult to predict which way it will pan out.
Simultaneous elections may lower some bargaining costs without solving the deeper problems.
Coattail effects could cut both ways.
Regional parties themselves may resist any arrangement that appears to subordinate them to Congress on the national stage.
BJP’s organisational and resource advantages remain substantial.
Historical simultaneous elections occurred under different party-system conditions; drawing lessons from the 1952–67 period or from limited concurrent contests requires caution.
Finally, the hypothesis assumes a level of sustained opposition coordination that recent experience has not reliably delivered, though desperation could drive them towards it.
Conclusion
The hypothesis that simultaneous elections could help Congress–regional alliances work better, improve vote transfer through uneven seat-sharing, and thereby create an uneven electoral risk for BJP appears coherent and grounded in both arithmetic and historical precedent.
MGR formula shows that such arrangements can work when partners are willing to share power at different levels, with a mutually accommodative approach.
Staggered elections do raise coordination costs. Simultaneous polls would collapse those costs into a single bargain and align time horizons more closely. Given the large difference in resources between BJP and the opposition, this may still work in BJP’s favour.
Yet the same evidence that supports the potential also reveals its limits.
Trust remains scarce, vote transfer imperfect, and coattail effects double-edged.
For BJP, the risk is real but not automatically decisive.
For the opposition, the opportunity is real but depends on solving coordination problems that have repeatedly proved difficult.
A multi-assumption simulation can illuminate the ranges of possible outcomes.
Ultimately, the judgment is political: whether the probability of effective opposition consolidation under simultaneous rules outweighs BJP’s organisational advantages and the non-electoral benefits it associates with the reform.
If I were the decision-maker, there are far too many risks, and I would drop the idea of ONOP without even a simulation.
Note:
1. Text in Blue points to additional data on the topic.
2. The views expressed here are those of the author and do not necessarily represent or reflect the views of PGurus.
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