Nick Clegg has suggested that the Lib Dems could boycott any potential 'rainbow coalition' in the event of a hung parliament - raising the prospect of a second general election this year.
The Liberal Democrat leader said that the idea, popular on the continent, "would not work" at Westminster.
His comments came despite seat projections that suggest a multi-party alliance may be the only way any party can secure a majority.
Depending on the number of seats they hold in May, any refusal by the Lib Dems to consider such a tie-up could potentially trigger another general election.
Mr Clegg made the comments as he was quizzed about attempts by former Labour Prime Minister Gordon Brown to build a 'rainbow coalition' in 2010.
The Deputy Prime Minister said he did not think such a complicated grouping would have worked then - or now.
He said: "(Mr Brown) was sort of very adamant that he thought that one could create a sort of rainbow coalition of lots and lots of different, a sort of smorgasbord of, different parties.
"I do remember saying, I just don't think that's going to work.
"I still don't think that's going to work - and that might be actually more of a relevant question after May 7.
"I think this idea that you have a government with a whole array of single issue parties all pulling this way and that, I think it's a recipe for insomnia as votes will be strung out night after night after night in the House of Commons.
"But it's also a recipe for a messy way of governing the country."
Earlier this year senior Lib Dems slapped down the party's Business Secretary Vince Cable after he suggested they could enter a rainbow coalition with the SNP.
The party said it could not do a deal with a party that wanted to break up Britain.
Mr Clegg has also told voters they should go the ballot box on May 7 expecting another hung parliament and the possibility of a coalition government.
Pollsters say some research suggests that voters are more likely to back a smaller party if they think there will be a hung parliament.
Mr Clegg said the electorate should think about which parties they would like to be working together in power after the election.
Asked about whether he would prefer a deal with Labour or the Tories, Mr Clegg said his personal views were "completely irrelevant".
"I don't think that my whims or wishes or my feelings or my likes or dislikes about this or that other party leader ... they are literally completely irrelevant," he said.
"The only thing that is relevant is what are the cards that are dealt to us by millions of people doing this wonderful thing, putting a simple cross next to somebody's name in a ballot box on May 7. They will tell us what combination is possible."
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