From left: Karnataka BJP chief BS Yeddyurappa, former Prime Minister HD Deve Gowda, and Karnataka Chief Minister Siddaramaiah (Photo of Yeddyurappa: Twitter/@BSYBJP | Photos of Deve Gowda, Siddaramaiah: Getty Images)

Will Siddaramaiah return as Karnataka's chief minister after next month's assembly election, or will the veteran BJP leader BS Yeddyurappa take his place?

It turns out that the Janata Dal (Secular), the party led by former Prime Minister HD Deve Gowda, could hold the key.

Three pre-poll surveys, including the India Today-Karvy Insights opinion poll, show that an alliance led by the JD(S) could win as many as 40 of the Karnataka assembly's 224 seats. In fact, the most conservative projection is 34 seats.

That's a significant number, considering that based on the poll numbers, the Congress and the BJP can hope to get a maximum of 101 seats, and 95 seats, respectively. Both these numbers fall short of the halfway mark in the Assembly: 112.

If either of the heavyweights manages to put together a post-poll alliance with the JD(S), the combined tally of seats would zoom past that mark.

THE NUMBERS | India Today-Karvy opinion poll says hung Assembly in Karnataka

Siddaramaiah believes the Congress will return to power with a clear majority. What's more, an ANI report - based on the chief minister's interview with a senior journalist - said he "refuted reports of forging a post-poll alliance" with the JD(S).

When India Today broadcast the results of its opinion poll, JD(S) spokesperson Tanveer Ahmed said his party wasn't the "B-team" of the BJP or the Congress, but the "A-team of the people of Karnataka."

Here are the seat share projections from the three opinion polls.

India Today - Karvy Insights

Congress - 90-101 | BJP - 78-86 | JD(S)+ - 34-43 | OTHERS 4-7

Times Now - VMR

Congress - 91 | BJP - 89 | JD(S) + BSP - 40 | OTHERS 4

JAIN-Lokniti CSDS Pre Poll Survey

Congress - 85-91 | BJP - 89-95 | JD(S)+ - 32-38 | OTHERS - 6-12

And here are the vote share numbers.