UKIP LEADER Nigel Farage would take on David Cameron, Ed Miliband and Nick Clegg in a televised pre-election debate, under proposals from broadcasters.
The Tory and Labour leaders would also go head-to-head in another programme, according to the joint plans from the BBC, ITV, Sky News and Channel 4.
The announcement - which follows months of detailed negotiations over the format for debates next year - is said to reflect “changes in the political landscape”.
Ukip came top in European elections in May, and secured its first elected Commons seat last week - while the Liberal Democrats have been languishing in the polls.
All parties have said they support more debates in principle, after the 2010 events dominated the campaign and drew significant audiences. But there have been disagreements about who should participate and how they will be staged.
The blueprint from the broadcasters would see former Newsnight host Jeremy Paxman chair a one-on-one contest between Mr Cameron and Mr Miliband for Sky News and Channel 4.
The Conservative, Labour and Liberal Democrat leaders would clash in a BBC debate presented by David Dimbleby.
And the trio will be joined by Mr Farage for an ITV programme chaired by Julie Etchingham.
The Ukip leader said the proposals recognised growing support for his party.
“The decision is better than it could have been. It does at least recognise the increasing popularity of Ukip,” he said.
“However if the political landscape continues to change we would expect and ask for inclusion in a second debate.”
The Liberal Democrats rejected the suggestion that they should be excluded from one debate.
“The Liberal Democrats have long argued that the debates last time round were of huge benefit to our democratic process and engaged millions of voters,” a spokesman said.
“The Liberal Democrats therefore welcome the fact that the broadcasters are seeking to make progress to ensure that the debates happen again in 2015.
“The Liberal Democrats, like the Labour Party, have publicly said that we would be prepared to sign up to the same 3-3-3 system we had in 2010.
“We do not accept the proposal that the Liberal Democrats, as a party of government, should be prevented from defending our record in one of the TV debates.
“That is the case we will make strongly in the negotiations that will now take place and we urge the other parties to join us around the negotiating table without excuse or delay.”
A statement from the broadcasters said the debates were “vital in engaging voters with the political process”. The three encounters at the last election, each featuring the Tory, Labour and Lib Dem leaders, were watched by 22 million people.
“The broadcasters intend to transmit the leaders’ debates live for all their extensive audiences, on air, online and on social media, which together have a mass reach amongst the British population,” the statement said.
Mr Farage was widely seen as emerging victorious from two debates with Mr Clegg on the EU in the run-up to European elections earlier this year.
Last week Mr Clegg accused Mr Cameron of “foot-dragging” over encounters during the general election campaign.
“The Tories should come clean - if they want to run scared, they should say they don’t want to do them, but not this endless ducking and weaving. I think people want the TV debates.
“The more people can see how the leaders measure up against each other, the better.”
A Conservative Party spokesman said: “We note the request and will respond accordingly.”
Ukip MEP Patrick O’Flynn posted on Twitter: “Progress 4 Nigel 2b included in one leader debate, but given our sustained electoral achievements we merit parity with Clegg as a minimum.”
Green Party leader Natalie Bennett said: “With these proposals the broadcasters are demonstrating just how out of touch they are with the public mood, and how ridiculously they cling to the idea that the future of politics looks like the past.
“It is clear from votes and polls that the public are fed up with the three business-as-usual parties and are looking around for alternatives.
“That is also demonstrated by the soaring membership of the Green parties of England and Wales and Scotland, now exceeding 27,000.
“Those members, the fast-growing numbers of likely Green voters (matching Lib Dems numbers), and the majority who back Green policies like bringing the railways back into public hands and the living wage for all workers would be seriously short-changed by debates from which we were excluded.”
Plaid Cymru leader Leanne Wood said: “The age of two-party politics is over and these debates should be a true reflection of the choice facing people in all corners of the UK at the General Election.
“Broadcasters have shown themselves to be out of touch by clinging on to the notion that there is no alternative to the tired Westminster elite.
“Plaid Cymru will be going into the general election with ambitious policies to improve public services and strengthen the Welsh economy.
“The people of Wales deserve nothing less than to hear what all parties have to offer them and we will be taking immediate steps to ensure that this happens.”
Mr Cameron’s official spokesman told a regular Westminster media briefing: “The Prime Minister has set out his views with regard to TV debates a number of times. His views haven’t changed.”
Mr Cameron suggested in May that he would like to see three debates, one pitting him against Mr Miliband as the two potential prime ministers, one involving the leaders of Conservatives, Labour and Liberal Democrats, and one also including Ukip and the Greens. The Prime Minister also suggested then that the debates could begin before the formal election campaign.
SNP Westminster leader Angus Robertson MP said: “These proposals will be utterly unacceptable to any democrat.
“What the London-based broadcasters’ are proposing fails in their duty to their viewers in Scotland, and simply doesn’t reflect the reality of politics across the UK today.
“The broadcasters have the cheek to say that their proposed format factors in ‘changes in the political landscape’ to justify including Ukip - entirely ignoring the fact that the SNP are now by far the third largest political party in the UK.
“Current Westminster voting intentions put the SNP in the lead in Scotland, and it is clearly wrong that the leader of the third biggest political party in the UK should be shut out of these network debates.
“Yet they are proposing to include Ukip, despite the fact the SNP won six seats at the last general election to Ukip’s none - and with the SNP at 40% in Scotland for the general election, to Ukip’s 4%.
“Despite the experience of the referendum campaign, the network broadcasters have once again forgotten their responsibility to Scotland. The BBC in particular as Scotland’s public service broadcaster should hang their heads in shame - under their proposals, the Tories and Labour would be included in four debates, the Lib Dems three, and the SNP just one. That is simply unfair to Scotland’s electorate.”
Speaking during a visit to Portsmouth, Mr Cameron said: “I’ve said many times I do favour the idea in principle, and that’s why we had debates at the last election.
“I will have a look at this proposal. I think there are some questions over it.
“Why have all the debates inside the election campaign, rather than spreading them out over a longer period? And also, why include some parties and not other parties?”
Asked if he would be willing to debate with Mr Farage, Mr Cameron said: “If you have one person, then the Greens have an MP as well, so you have to think these things through.
“It’s an interesting proposal. None of us had seen it beforehand. I’m sure we’ll study it and I’m sure there will be other proposals along before long.
“I’ve always been in favour of TV debates. I’m in favour of TV debates, but you’ve got to make sure you come up with a proposal that everyone can agree to, and I can’t see how you can have one party in that has an MP in Parliament, and not another party.
“I’m sure clever people can get together and sort these issues out, but they do need to take these sorts of points into account.”