The UK Independence Party may avoid putting up candidates to contest the seats of existing Eurosceptic MPs, its party leader has said.
Nigel Farage ruled out a formal electoral pact, but suggested he would not oppose agreements made at constituency level.
Negotiations may prove tricky however, after Foreign Secretary William Hague insisted Tories "don't make pacts with other parties" and instead issued a caution to wavering supporters that they risked letting Labour into power.
A number of high-profile Conservatives have floated the possibility of an alliance with Ukip in the run-up to the election to avoid splitting the right-wing vote, including Jacob Rees-Mogg who suggested that Mr Farage's party would expect to get some MPs out of any deal.
Writing in The Times, Mr Farage said: "If either they, or others like them, even Labour MPs, with their local associations, chose to propose running on a joint ticket then I would leave the local Ukip association to have those associations.
"If after discussions they feel that it would be a better way to serve their constituents, then I and the National Executive Committee would be happy to hear reasoning. After all we are a party that believes in real localism and doesn't think that the centre is the repository of all wisdom."
A ComRes survey found 22 per cent of Tory local councillors supported an agreement between the two parties, but Mr Hague told BBC Radio 5 Live: "I do rule that out.
"We don't make electoral pacts with other parties; we do make pacts with the voters of other parties and win over the voters of other parties, as we've often done through history.
"And, of course, if someone is contemplating voting Ukip who would otherwise vote Conservative they could, by default, produce a Labour government which is the absolute opposite of what they might want on Europe for instance.
"They might be voting for Ukip because they want to have a referendum on Europe. Well, they are only going to get that if David Cameron is prime minister after the next election.
"Whatever they have done in local elections or whatever they say in opinion polls, at the next general election a voter like that will have to choose: are they going to have Ed Miliband as prime minister and go headlong into giving away more of the country's powers? Or are they going to have a referendum under David Cameron?
"A general election in this country is a first-past-the-post system. It is a choice."
The Ukip leader is tipped to draw a big crowd after being invited to speak this week at a fringe Conservative Party conference event at Manchester town hall - one of the largest venues.