Labour and the Conservatives are both becoming more ideological, Liberal Democrat Danny Alexander has said.
Speaking on ITV's The Agenda, the Chief Secretary to the Treasury said: "Labour is becoming more, kind of, left-wing, the Tories are becoming more anti-European.
"And I think both of those things mean you can't have the Tories or Labour by themselves anymore."
On suggestions he had "gone native" at the Treasury, Mr Alexander said that on the contrary, "the Treasury has been captured by the Liberal Democrats... George Osborne's the hostage".
Danny Alexander, the chief secretary to the Treasury, will join ITV News Political Editor Tom Bradby on the latest edition of The Agenda tonight.
He will be joined on the 10.35pm programme by writer and broadcaster Clive Anderson, the journalist Amanda Platell and Germaine Greer, the academic and writer.
The Chief Secretary to the Treasury, Danny Alexander, will join ITV News Political Editor Tom Bradby on The Agenda tomorrow night, Monday 17th February.
Catch up on the last episode here with the Chancellor George Osborne, Former BBC Economics Editor turned JP Morgan strategist Stephanie Flanders, historian and broadcaster Bettany Hughes and money saving expert Martin Lewis.
The Agenda with Tom Bradby is on ITV at 10.35pm on Monday night.
London mayor Boris Johnson has repeated his call for the tax rate to be cut to 40p - and declined to rule out the possibility of it happening before the general election.
Earlier, the Liberal Democrat Chief Secretary to the Treasury - Danny Alexander - said the rate would be cut "over my dead body".
"The last thing I want to see is a pointless sacrifice from the Liberal Democrats, let alone the dead body of Danny Alexander," he told BBC Radio 4's Today programme.
"Sooner or later there will have to be a new Conservative manifesto and I can't believe we are going to go into an election on a campaign to keep our tax rates higher."
Asked if that meant he accepted it could not happen until after 2015, he said: "Who can say what will happen to Danny Alexander? Stranger things have happened at sea."I don't think that it is reasonable always to keep UK tax rates higher than those of competitor countries.
"UK income tax is now higher than the average in the EU. That never used to be the case. I don't see why it should be the case for the long term and I see no reason why we shouldn't bring it down."
Chief Secretary to the Treasury Danny Alexander said the Liberal Democrats would not allow a cut to the top rate of tax in this Parliament.
In an interview with the Daily Mirror, he was asked about David Cameron's refusal to rule out cutting the top rate and replied: "You'll have to ask them (the Tories) why they answer those questions in those ways.
"If you ask me would I cut the top rate below 45p the answer is 'no'. In this Parliament we will not allow that to happen."
Mr Alexander also had some praise for Labour's Ed Balls - amid questions over whether the Lib Dems could work with the party in a future coalition.
"I play cricket with Ed Balls. I have opened the bowling at Lords while he kept wicket behind the stumps and I have to say he didn't let anything past him. So I would endorse him as a wicket keeper," he said.
Danny Alexander, the Liberal Democrat Chief Secretary to the Treasury, said any cuts to the top rate of tax before the next general election will be "over my dead body".
Mr Alexander made the comment as he dismissed calls from some Tories who want to see the rate reduced from 45p to 40p before the 2015 poll.
David Cameron fuelled speculation by repeatedly refusing to rule out further trimming the rate for those earning over £150,000 a year. It fell from 50p last year.
But in an interview with the Daily Mirror, Mr Alexander said: "I think it is right at 45%. I wouldn't go to cutting below 45%.
"I would say that would happen over my dead body.
Lib Dem Chief Secretary to the Treasury Danny Alexander said "Labour's hypocrisy on taxation is breathtaking" after Ed Balls set out the party's economic policy ahead of the 2015 General Election.
Mr Alexander said the shadow chancellor's speech shows the party "have learned nothing from the last few years and would undermine the foundations of Britain's economic recovery" and reintroducing the 50 pence tax rate "wouldn't help".
He said: "In Government they left a system full of loopholes for the wealthy to exploit.
"Thanks to our action in Government to raise capital gains tax, reduce pensions tax relief for the wealthiest, and tackle avoidance, Lib Dems in Government are raising more from those who have the most and making Britain more competitive."
Chief Secretary to the Treasury Danny Alexander said Lord Rennard should not be readmitted to the House of Lords until he has apologised for "the serious harm caused by his behaviour."
Mr Alexander said he agreed with Alistair Webster QC, who reviewed the evidence in the Lord Rennard case.
He told Sunday Politics: "[Webster] has made clear, while he can't prove what has happened to a criminal standard, that it's clear there has been considerable distress and harm caused to a number of women in the party.
"I agree with him on that and that's why I think it's necessary for Chris Rennard to apologise as he's been asked to do and [it's] totally unacceptable if he doesn't make that step."
Mr Alexander added: "[Nick Clegg's] view is and my view is, that Lord Rennard should not be readmitted to the group in the House of Lords until he has made a full apology for the serious harm that has been caused by his behaviour. If that isn't forthcoming, he shouldn't be readmitted."
Lord Rennard strenuously denies claims against him.
The Chief Secretary to the Treasury has waded into the row over a demand by 95 Tory backbenchers for the UK Parliament to get a veto over EU legislation.
It comes after the Foreign Secretary William Hague said a single market could not work on that basis.
Danny Alexander told ITV News: "William Hague is absolutely right. The idea is potty.
"It is one that is not going to happen and I think that those backbenchers who keep putting forward those sorts of ideas should just come out and accept that what they really want is for Britain to leave the European Union because that is the argument they are actually making."
He added: "These sort of salami-slicing tactics against their own leadership are bad for Britain, they are bad for our economy."
The Chief Secretary to the Treasury Danny Alexander has defended the Government's plan to allow councils which give fracking the go-ahead to keep 100 per cent of the business rates they collect.
Asked if that amounted to a bribe, he told ITV News: "Fracking offers a significant opportunity for the UK economy. It's a potential source of considerable amounts of energy for our country.
"In common with other areas of energy development where local authorities are allowed to keep business rates, and where there are other incentives for communities - it's important and fair we should treat fracking in the same way."