Tim Farron has refused to rule out a coalition between the Liberal Democrats and the Conservatives if neither party gets an overall majority after the 8 June election.
The Lib Dem leader did not give a direct answer when asked if his party would enter into a coalition similar to that which came out of the 2010 election.
It comes after veteran Lib Dem politician Vince Cable – who announced on Tuesday he would be running again for the Twickenham seat he lost in 2015 – ruled out an electoral pact with Labour, claiming that “the prospect of the Labour Party holding the balance of power, or getting into power are so remote” that the subject is not worth talking about.
The Green Party has also called for talks with Mr Farron and the Labour leadership with the aim of forming a “progressive alliance” for the upcoming June general election.
Party co-leaders Caroline Lucas and Jonathan Bartley said the three parties should work together and might stand aside for each other in some seats to “stop the Tories wrecking our country”.
In the Commons during a debate ahead of the vote on triggering the election process, SNP MP John Nicolson asked Mr Farron: “Will you rule out a coalition with the Conservatives, yes or no?”
Mr Farron avoided giving a clear answer, replying: “The great problem we face in this country is that the Prime Minister is running on the expectation... there will be no need for any form of coalition with anybody.”
He was then heckled by Mr Nicolson, who repeatedly asked: “Yes or no?”
Mr Farron continued: “The Prime Minister will call this general election in order to take advantage of what she thinks is a clear opportunity for a majority of a hundred or more.
“It is very clear that we’re not talking about a balanced parliament. The Prime Minister takes the view that in calling this election is the opportunity for her to have a 100-seat majority.
“An opportunity for her to drive through not just a hard Brexit but indeed her agenda to slim down the national health service, to slim down...”
To further calls of “yes or no?” from MPs, Mr Farron said: “The reality is we are not looking at a balanced Parliament. The Prime Minister has clearly called this election on the understanding that she can give herself the majority that will allow herself to deliver the hardest form of Brexit, to shrink our national health service, to undermine the support for our education and to take us out of the single market.
“If you want to avoid a hard Brexit, if you want to keep Britain in the single market if you want a Britain that has a decent opposition, then only the Liberal Democrats will give you the final say.
“May I point out there is only one route to the Prime Minister losing the general election, and it is a Liberal Democrat route.”
He added: “The only outcome of this election that does not lead to a Conservative majority is the Liberal Democrats revival and growth in every part in this country.”
Mr Farron has also been attacked for suggesting gay people are sinners, a view likely to be at odds with the majority of liberal Remain voters his party has been working to win over.
When interviewed on Channel 4 News, he refused to deny that he thought homosexuality is a sin, but said he would not “make theological arguments”.
Nick Clegg, who faced criticism in 2010 as the party’s then leader for leading the Lib Dems into a coalition with the Tories, has announced he will stand again for election.
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