The Liberal Democrats should be given the keys to the Department of Education in any future coalition, Nick Clegg said, pledging he will make increases to education funding a key demand for participation in another government as they launch a manifesto promising to spend billions more than the Tories or Labour.
Clegg said the pledge to ensure as much was spent per youngster "from cradle to college" over the next parliament was central to the party's message of "opportunity".
It is one of five policies featured on the front page of the manifesto - marking it out as an effective "red line" in post-election negotiations.
Nick Clegg, leader of the Liberal Democrats, left, and Tom Brake, candidate for Carshalton and Wallington
Speaking to the Guardian, Clegg said he wanted the Lib Dems to run the Department for Education, claiming it was his party who had run education reform - not former Education Secretary Michael Gove.
Clegg told the Guardian the five - also including £8 billion a year extra NHS spending and mental health parity, a £12,500 income tax allowance, balancing the budget by 2017/18 and five green measures - enjoyed "a near religious status".
But senior Lib Dem David Laws refused to name red lines for the party in post-election negotiations.
Speaking to the Radio 4 Today programme, he said: "We are highlighting on the very front page of that manifesto the key priorities of our party so people can see very clearly if they vote Liberal Democrat on May 7 what we will use our voice to achieve in the next parliament, whether we are in government or not."
Laws rejected suggestions that the Lib Dems would have no mandate to deliver policy if they lost scores of seats in May.
He said: "If there is no majority for any one party after the election on May 7 we would have a responsibility on behalf of the wider country, but particularly our own voters, to do everything we could to deliver a stable government and to deliver as many of the policies in our manifesto as possible.
"If you have a coalition government ... no party in coalition can deliver all of its manifesto."
He added: "If people are fair to the Liberal Democrats they will recognise we have achieved a huge amount of our 2010 manifesto."
On red lines, Laws added: "I think you can read into it, including the lessons we have had in government over tuition fees, that if we put these things on the very front page, the cover actually, of our manifesto we will expect to deliver these in government.
"It's not sensible to go through a manifesto of about 150 pages and pick out of all of those policies the things that would and wouldn't be red lines before we even know what the make-up of the next parliament will be.
"It's an idiotic way of negotiating and we can't possibly do that."
The Lib Dems said the pledge to raise the education budget for two to 19-year-olds in England to £55 billion by 2020 would protect spending per pupil even as the number of children enrolled in classes increases, and was £5 billion a year more than the Tories were promising and £2.5 billion more than Labour.
Under the blueprint, the education budget - covering nurseries, schools and colleges - would be maintained in real terms until the structural deficit is eliminated in 2017/18 - a reduction in per-pupil funding.
But above-inflation increases in line with economic growth after that would bring it back in line with today's levels by the end of the five-year parliament.
Clegg, who will give further details of his approach to coalition negotiations at the launch, said the party would campaign "very hard" on education issues in seats where they face a Tory challenge.
"The manifesto has one simple ambition and word at its heart: opportunity," he said.
"Education is the great liberator of people's potential so we need to make sure we support the education system in the next parliament to give every boy and girl the chance to thrive."
He said: "Both the Conservative and Labour parties want to cut the amount of money going into schools and nurseries and colleges because their plans don't keep up with extra pupil numbers."
Laws said the party's deficit reduction plans, which are based on the economy growing, had contingencies of "billions of pounds" in case there is a downturn.
The Schools Minister told BBC Breakfast: "What I'm saying is that we are planning to balance the current budget by 2017/18 but the plans that we published a couple of days ago don't just balance it to zero, but there is actually a contingency in there of a number of billion pounds beyond the level that we would need to get that.
"So we're being extremely prudent and cautious, we've published all our figures in much greater detail than all of the other parties a couple of days ago,and to my knowledge they have survived all of the scrutiny they have had since then in a way that the other parties' simply haven't."
“Voters know no main party is going to win," Clegg told the Guardian. "Their leaders are charging round the country pretending they are going to get an overall majority, but in their heart of hearts they know it is not true, you can see it in their eyes.
"Do you want David Cameron, accompanied by Nigel Farage, dancing to the tune of swivel-eyed rightwing backbenchers, or do you want a hapless Labour minority administration dancing to the tune of Alex Salmond?”