The polls, published in the Mail on Sunday and the People newspapers, both put the Tories nine points ahead of Labour. Two polls on Saturday also hinted at a hung parliament.
A lead of up to nine points is unlikely to give the Conservatives an overall majority, resulting in a hung parliament for the first time since the mid 1970s.
It is understood that David Cameron is considering a plan that could see him call a snap election before the end of 2010 in a bid to secure a bigger majority.
A hung parliament would make financial markets jittery because it would impede Cameron’s ability to tackle Britain’s record budget deficit.
The BPIX poll for the Mail on Sunday showed a slip in Tory support, putting them on 39 per cent, Labour on 30 and the Liberal Democrats on 18. It is the first time in more than two years that Tory support has fallen below 40 per cent in a BPIX poll.