David Cameron is heading for an explosive row with his party over MPs' pay as leading Tory backbenchers today call on him to show "leadership" by backing a salary increase of up to 11%.

The issue is coming back to haunt the prime minister just months after he, Nick Clegg and Ed Miliband all condemned the idea of a big one-off rise put forward by the Independent Parliamentary Standards Authority (Ipsa), which was put in charge of MPs' pay following the expenses scandal. All three leaders said then that MPs could not be seen to accept an 11% pay rise – from the current £66,396 a year to £74,000 from 2015 – at a time when most people are seeing their real wages decrease.

Now, however, with a public consultation on Ipsa's proposal ending on Sunday and final recommendations due within weeks, Cameron has to decide, once and for all, whether to back the independent body or render it meaningless by rejecting its suggestions. Influential Tories say Cameron should perform a U-turn and resolve the pay issue rather than bow again to fears of a public backlash.

The vice-chairman of the 1922 committee of Conservative backbenchers, Charles Walker, told the Observer that settling salaries was "always going to be messy" and that there would never be a good time. Since Ipsa was set up to sort out the pay and conditions of MPs in the aftermath of the expenses furore, parliament would look ridiculous if it now rejected its recommendations because they were politically inconvenient.

"They [the party leaders] can either respect the independence of Ipsa or bring forward a motion to have it scrapped. The attraction of the second option is that it would negate any pay rise for members of parliament. However, the obvious downside is that it would once again place the toxic issue of remuneration directly back into the lap of the House of Commons and the prime minister who, during the expenses crisis, said members of parliament should have nothing further to do with the setting of their terms and conditions."

Walker added: "What is required is a bit of leadership and courage, with the PM saying that, while the Ipsa recommendations aren't ideal, respecting the independence of this body must be better than returning to the failed system of the past, which nearly shattered faith in our democracy."

Another senior 1922 committee figure said: "It is beyond doubt that the prime minister has to accept Ipsa's recommendation. Parliament gave it the power to decide. We cannot now withdraw that power because it looks bad. We gave it independence to take the issue out of the hands of MPs."

It is understood that the 1922 committee has made its view clear to Cameron. Sources said that Downing Street may seek a way out of the impasse by publicly disagreeing with Ipsa's recommendation, but conceding that it has been empowered to make the final decision, and that its word on salaries is final.

If Ipsa sticks to its initial proposal in its final report, the salary rise would come into effect from 2015, costing taxpayers an extra £4.6m a year. At the same time, MPs' generous pensions and "golden goodbyes" would be reduced and there would be a tighter regime on expenses, including those for dinners and taxis.

Miliband said in the summer that he did not think MPs should be taking double-digit pay rises when nurses and teachers were facing pay freezes or very low increases. Clegg said he was sure "the package should not go ahead, full stop", and made clear he would not take the extra money if it was agreed.

A Downing Street spokesman said the prime minister would wait for Ipsa's final report, adding: "The cost of politics should go down, not up. And MPs' pay shouldn't go up while public sector pay is rightly being constrained."