But a third London-focused survey has Ed Miliband's Labour streaking ahead.
TNS has the Conservatives marginally ahead on 33% to Labour's 32%, each down one point. Ukip were on 14%, down one, and the Liberal Democrats on 8%, up one.
The pollster said both main parties are stuck in the margin of error. It said voter turn-out would be around 69% on average, with more voters taking part in Scotland than the rest of the country.
Michelle Harrison, head of political and social at TNS, said attention was now turning on what happens if no party secures overall majority and "whether the party with the most seats or the biggest share of the vote can claim the greatest legitimacy in forming the next government".
She said: "We are witnessing a Britain in political flux and after a lackluster election campaign, the real drama starts on Friday."
The results of a final Guardian/ICM poll has the parties even closer, tied at 35%.
The poll says Labour has pulled back three points on the previous campaign poll, published nine days ago. The Tories numbers remained unchanged.
The Guardian poll had the Liberal Democrats unchanged on 9%, and the the Scottish National Party up one to 5%.
Meanwhile, a poll by YouGov for the Evening Standard had Ed Miliband's Labour 13 points ahead among Londoners. The party gained two points in a fortnight to hit 46%, its best share since November 2013, the newspaper reported.
The parties gains came as both Ukip and the Greens support dropped. Nigel Farage's party was down two points to eight, and the Greens fell to 3%, dropping two points. Both drops are crucial as they could have a domino affect on other parties overall numbers.
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Labour’s poll lead, according to the Evening Standard research, is its biggest since last May when it had its best local election results for a generation. The result marks a swing of 5.5% from the Conservatives since the 2010 election.
The Standard suggests that Labour could win eight to 10 seats in the capital, and if that was replicated across the UK, a hung parliament was likely.
YouGov’s Laurence Janta-Lipinski said the election was "one of the closest" in living memory.
She told the Standard: “With key Conservative and Labour marginals across the capital crucial to the national outcome, all eyes will be on seats such as Croydon Central and Finchley & Golders Green as parties and pundits alike hope to get an idea as to what the next government will look like.”
In a separate poll of undecided voters, ComRes found four out of 10 said a Labour government supported by the SNP was their least favourite potential outcome.
Just a third of the panel, which has been polled several times over the course of the campaign for ITV's Good Morning Britain, told the pollster they had definitely decided who to vote for.
More than one in 10 (13%) of these voters remain completely undecided while two in five (42%) say that they have a good idea who they are going to vote for but are not yet completely sure.
Whether the government that is created can survive five years remains to be seen. The Fixed-Term Parliament Act.
"First, if more than two thirds of the House of Commons vote to call an election – and that means 434 of the 650 MPs, not just two thirds of those in the chamber," Catherine Haddon from the Institute for Government think-tank said.
"The second is more complicated. If a motion of no confidence is passed or there is a failed vote of confidence, there is a 14-day period in which to pass an act of confidence in a new government. If no such vote is passed, a new election must be held, probably a mere 17 working days later."Suggest a correction