The leader of Ukip Nigel Farage has held secret talks about working with anti-European Union Conservative MPs in preparation for a hung parliament.
He disclosed the contact when he was unveiling the party's general election pledge card outside the London offices of the European Commission in London.
Mr Farage said: "It is likely that the next government in this country won't be a two-way party coalition or deal, it will be a three-way party coalition or deal."
Asked if he had had any "conversations with Conservatives not currently Ukip about working with them after the election", he said: "Not really."
Pressed further, he said: "Not formally no. Informally in politics, round the corner, in the places that politicians frequent, these sort of conversations happen all the time.
"We are committed to using whatever influence we have in parliament to get a referendum. There are some in the Conservative party who are very keen for that to happen, others [less so]."
Mr Farage confirmed that these talks were with unnamed Tory MPs, not ministers.
Mr Farage, who has said that he would stand down as Ukip leader if he is not returned as an MP after May's election, said that he faced "a hell of a fight" to win in south Thanet.
The Ukip leader unveiled the party's pledge card - which he admitted was very "Blairite" - which made no mention of immigration.
Instead there was a vaguer commitment to "control our borders". Mr Farage played down the omission, saying people were "not obsessed with immigration as a subject" but about the changes it wrought on their communities.
Meanwhile in Scotland, Nicola Sturgeon said that her party aims to join with other "progressive parties at Westminster to work for the common good" across the UK.
The Scottish first minister joined activists to campaign in the east end of Glasgow yesterday following the SNP party conference in the city over the weekend.
Polls continue to suggest that the nationalists could win dozens of seats in the election and hold the balance of power at Westminster.
The membership of the party has soared since last year's referendum, with more than 102,000 now signed up.
In her conference address Ms Sturgeon vowed to "shake up the Westminster establishment'' and make the rest of the UK take notice of Scotland in the election campaign.
In Glasgow yesterday, she said a vote for the SNP was an opportunity to end austerity, reject the renewal of Trident and win "real power" for Scotland.
She said: "We can achieve an end to the austerity cuts - implemented by the Tories and backed by Labour - which are causing so much damage."
IT could be argued that the most pressing need for British prime minister David Cameron is not to fashion a better relationship with the Liberal Democrats. It is to fashion one with his own party. A minority government would exacerbate the headache of coalition politics. But with the Conservatives and Labour roughly equal in the polls, a Labour/SNP alliance is still likely. But let's look at another possible scenario, which none of the parties want to talk about.