David Cameron has refused to say whether he would turn down the £8,000 pay rise being offered to MPs by the independent body that sets politicians' salaries.
On Thursday morning the Independent Parliamentary Standards Authority (Ipsa) proposed that MPs see their pay increase from £66,396 to £74,000 in May 2015.
Ed Miliband has said the pay rise should not go ahead given the current squeeze on public sector pay.
"I don't think MPs should be getting a 10% pay rise when nurses and teachers are facing either pay freezes or very low increases and people in the private sector are facing similar circumstances," he said.
"If this was to go ahead I wouldn't be accepting this pay rise but I don't think it is going to go ahead in the current circumstances because I think that when Ipsa consult the public, the public will be pretty clear that while the difficulties we have in the economy persist we can't have MPs getting a 10% pay rise."
Nick Clegg has also said he would not accept any pay rise as it would be "impossible to explain to the public".
"There are millions of people in the UK who have had a remorseless squeeze on their living standards," he said last week.
"I would certainly seek to do whatever I can to see that either this decision is not taken in the first place, but secondly if it were to be taken not to take that pay increase."
However quizzed by reporters on Thursday morning over whether the prime minister would also turn down the pay rise, Downing Street refused to be drawn.
The prime minister's official spokesperson said this was because "there is not a pay rise taking place" as Ipsa's plan was merely a proposal.
"He [Cameron] doesn't agree that the cost of politics should go up, it should go down, nor does he think MPs pay should be going up while public sector pay is being constrained," the spokesperson said.
Many backbenchers fear a backlash from voters who would not understand why politicians should see their pay increase by such a substantial amount - even though MPs are not responsible for setting their own salaries.
Lib Dem MP Roger Williams said it was right that MPs' pay was set independently, but said the rise being recommended by Ipsa was too high.
"I think MPs are as shocked as the public about this proposal. I think that there is cross-party consensus that it is completely inappropriate to have a rise of this scale," he told the Today programme.
"It comes as a great disappointment to me that in making this recommendation, it may be based on some comparable figures and salaries, but it hasn't taken into account public opinion."
And education secretary Michael Gove was less circumspect than Downing Street. He told ITV News Ipsa was a "silly organisation really" before adding: "as far as I'm concerned about this pay rise they can stick it".
Unions immediately demanded matching 11% increases for their members. RMT general secretary Bob Crow said: "Be in no doubt, RMT will be fighting for pay rise parity with MPs in all of our negotiations and will have no hesitation in striking to get for our members what the politicians have got for themselves.
"If inflation-busting pay increases are good enough for the political class then they are good enough for nurses, transport workers, firefighters and the rest of the working class. If MPs want to unleash a pay free for all then you can bet your life RMT will be in there fighting to make sure our members get their share of the all."
Dave Prentis, general secretary of Unison said: "The union has always supported the independent pay review body system, it is a straightforward mechanism for delivering fair pay.
"But, since the government came to power, they have run roughshod over it by demanding the imposition of a pay freeze followed by just 1% until 2016.
"The very idea then that MPs should enjoy an exemption and take a 9% increase will rightly cause outrage amongst workers up and down the country."
Sir Ian Kennedy, the chairman of Ipsa, defended the plan. Speaking to BBC Radio 5 Live on Thursday morning, he said the current pay level was "not fair to MPs and not fair to the taxpayer".
"Taxpayers deserve to have an MP who is properly remunerated," he said.
And he said if politicians were not paid more it would be "running sore" among MPs. "It will cause MPs to pile in to say this, that or another about their renumeration."
"I think because there is never a right time, now is as good a time as any to say we've got to end this running sore of political life."
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