MPs could lose the right to debate and vote on their own pay after a review was announced by the government.
Ms Harman confirmed the pay system would be reviewed
They are to debate in a fortnight a proposal for a 2.8% rise, but Gordon Brown has urged MPs to accept 1.9%, in line with public sector workers.
Commons leader Harriet Harman told MPs it could be "possibly the last time" they debate and vote on their own pay.
The review is to examine using "objective criteria" to establish MPs' pay, so MPs are not required to vote.
Ms Harman said: "Many members say they find it unacceptable, and we know the public don't accept that MPs decide by voting their own pay and pensions."
MPs' AND MINISTERS' PAY
MP - £60,675
Minister of state - £100,568
Cabinet minister - £137,579
Prime minister - £188,849
Source: Commons information office
"We therefore intend to review the procedures for setting MPs' pay and pensions in the future, with a view to examining options that find objective criteria for pay determination within a framework that does not require members to vote."
MPs currently vote on their own pay rises - which are based on recommendations from the Senior Salaries Pay Board.
The board's report is due to be published on Wednesday and is expected to recommend a 2.8% rise for MPs, on the current £60,675 a year.
But the prime minister has urged them to demonstrate the "discipline that we ask of other people" and keep increases below 2% - in line with those of public sector workers like nurses and police.
The government's decision to award in two stages the 2.5% pay rise recommended for public sector workers, means they are effectively getting 1.9%.
That has prompted anger from public sector workers including police officers, prison guards, nurses and civil servants.
While the prime minister can state his preferred figure, MPs will have the final say on their pay rise through a free vote in the Commons.