Labour leader Ed Miliband has called on David Cameron to block any million pound-plus bonus payout to the chief executive of the predominantly state-owned Royal Bank of Scotland.
Mr Miliband sought to pile on the pressure on the Prime Minister over bank bonuses, challenging him to ensure Stephen Hester did not receive another seven-figure award.
Mr Cameron said last week that any bonus paid to Mr Hester would be a "lot less" than the £2 million he was given last year than, but would not go further.
His comments came after Sir Philip Hampton, the chairman of the bank which is 83% state-owned, said a report that the board wanted to pay Mr Hester between £1.3.and £1.5 million was "inaccurate and premature".
The calls to curb Stephen Hester's bonus come after a week in which MPs seriously considered stripping the former RBS boss Sir Fred Goodwin of his knighthood.
In an interview with The Observer, Mr Miliband said it was now up to Mr Cameron to make sure there was no award on that scale.
"David Cameron has said on numerous occasions that he would stop banks paying out big bonuses. He has also called upon shareholders to stop excessive executive pay," he said.
"The best thing that could happen is that top management at RBS recognises the need for restraint. But if it doesn't happen, Cameron should act to stop Stephen Hester being paid a bonus of this scale.
"David Cameron will be judged by his deeds, not his words."