Midnight approaches, meaning it's time to wrap up today's Politics Live blog. Here's a recap of the day's big political developments:

• Downing Street has declared David Cameron will only participate in one leaders' debate - and ruled out a head-to-head with Ed Miliband

• Labour, the Liberal Democrats and UKIP have criticised the prime minister's stance

• Fresh polling from Lord Ashcroft indicates the SNP are on track for substantial gains in Scotland - including taking Labour's safest seat

• The SNP's Alex Salmond has reaffirmed his party's interest in a deal with Labour and declared his party is enjoying "massive support" north of the border

• The debate over immigration has continued after Nigel Farage's speech and Ed Miliband's focus on the issue in PMQs

The campaign countdown continues tomorrow from 6am GMT - join us then.

And here's the Lib Dem response to Downing Street's letter. A spokesperson says: "The public want these debates to happen and it is not right for one party to dictate their terms to try and gain an advantage. The Tories clearly do not want to discuss and debate the merits of their manifesto with the British public - it's why they don't want them to happen during the campaign - but the Liberal Democrats do. David Cameron and the Conservatives should stop thinking they can hold these debates to ransom."

We have been reporting the findings of a series of opinion polls conducted by Lord Ashcroft which make for very interesting reading and which have prompted a lot of political reaction, particularly in Scotland. The Conservative Home website, external has published a presentation the peer made earlier in which he set out his thoughts on the state of the polls two months ahead of the election.

A UKIP party spokesperson responds to Downing Street's TV debates letter: "After praising what a good thing debates were for democracy as recently as 2014, why is David Cameron now acting chicken and running as far away from them as possible?"

The Daily Telegraph

Image source, Telegraph

Home Secretary Theresa May is being advised that anti-drugs lessons might be counter-productive, the Telegraph reports, external.

tweets, external: debates should not be cosy deals between parties. Rules should be agreed by @ElectoralCommUK and @Ofcom and parties should have to comply

The Guardian

Image source, Guardian

The Guardian highlights BBC Trust chair Rona Fairhead's call for a major shake-up of corporate governance at the broadcaster.

BBC News Channel

Lance Price, a former adviser to Tony Blair, says David Cameron's stance on election debates is "entirely predictable" and suggests that the PM will pay a "heavy political price" for his decision to "run scared". While politicians have ducked out of debates before, he tells the BBC News channel that Mr Cameron is different because he was "so enthusiastic" about debates in 2010 when he was opposition leader. A seven-way debate will not be "very satisfactory", he adds.

The Times

Image source, Times

Tomorrow's Times previews the final Budget of the parliament, which it reports could feature a pre-election giveaway, external for workers. That, at least, is the fear of senior Labour figures.

Image source, Getty Images

Labour has responded to David Cameron's TV debates demands with a statement from Douglas Alexander, the party's general election strategy chair. He says Labour continues to support the broadcasters' proposals, before adding: "This is an outrageous attempt from the prime minister to bully the broadcasters into dropping their proposals for a head-to-head debate between David Cameron and Ed Miliband. That it comes only hours after Ed Miliband called David Cameron's bluff and said he would debate him any time, any place, shows the lengths David Cameron will go to run scared of a debate with‎ Ed Miliband."

The Independent

Image source, Independent

The Independent's front page features a striking story, external concerning Lord Gus O'Donnell, the former head of the civil service, who attacks the political classes for not being sufficiently rooted in reality.

tweets, external: UK's never had a Chinese-heritage MP. But now 3 PPCs in May: Alan Mak (Con Havant), Steven Cheung (LD Walthstow), Philip Ling (LD Tooting)

tweets, external: Lots of outrage against Cameron kiboshing TV debates. Can't share it. The broadcasters have been stupidly arrogant. Got what they deserved.

BBC Newsnight
BBC Two, 22:30

Dame Anne Begg, the Scottish Labour MP, is on Newsnight responding to this evening's polls from Lord Ashcroft. "This is not a pleasant place to be," she admits. "I'd much rather we were doing better, but often when our back's against the wall that's when Labour comes out fighting - and we will be fighting in every constituency to hold on to what we've got." Former Scottish first minister Alex Salmond told the programme that the SNP would not work with the Tories, but Dame Anne pointed out the nationalists were happy to cooperate with Scottish Conservatives when they governed as a minority. "I think the people of Scotland are a bit cannier than perhaps Alec gives them credit for," she says, before warning: "The person who will be the most smug if the SNP continue to do well will be David Cameron."

BBC Newsnight
BBC Two, 22:30

The SNP could never do a deal with the Conservatives, Alex Salmond tells Newsnight, but a Labour-SNP alliance is very plausible. "We think we can do business with the Labour party and use the influence that Scotland has to make sure that progressive politics… can be brought to bear," he says. "Working with our allies in Plaid Cymru we can be a progressive and perhaps decisive force in the next parliament."

The Guardian

Tony Blair is donating £1,000 to each of Labour's 106 target marginal seats, the Guardian reports, external. Writing to the candidates who'll benefit from his donation, the former prime minister says: "I have every confidence that with your drive, determination and organisational skills, you will deliver a successful local campaign that will also see our party returned to government." The cash boost has been welcomed by party HQ, but a spokesperson insisted Labour's campaign "is based on millions of conversations with people on their doorsteps and in their communities".

BBC Newsnight
BBC Two, 22:30

Image source, PA

Alex Salmond has been interviewed on Newsnight after Lord Ashcroft's polls suggested the SNP are set to make big gains in Scotland. "We're trying to keep calm," he says, after declaring the change underway north of the border represents a "new direction for politics" that will result in "the breaking of the Westminster establishment".

tweets, external: New poll suggests that even Wee Jimmy, who just joined the SNP for a laugh, will take a safe Labour seat.

tweets, external: Cameron knows Ed Miliband would destroy him in a one-on-one debate. Our PM is nothing but a coward and a chicken #tvdebates

tweets, external: @David_Cameron The British public want the debates so let's get on with it. Stop holding them to ransom by trying to dictate the terms.