Oklahama Senator Don Nickles, who is number two Republican in the Senate, told ABC's This Week programme that there were other senators who would make more effective leaders.

This is bigger than any single senator now. I am concerned that Trent has been weakened to the point that may jeopardise his ability to enact our agenda and speak to all Americans Senator Don Nickles

He said Mr Lott had been weakened to the point that he jeopardised his party's agenda in the new Congress.

Mr Lott has apologised several times for remarks he made that apparently condoned racial segregation in the United States.

Mr Nickles has been deputy to Mr Lott in the Senate for six years and is seen as a potential rival, should a leadership election be held.

Ability questioned

He said he accepted Mr Lott's apologies for suggesting that the US would have been better off if segregationist candidate Strom Thurmond had been elected president in 1948.

But he added: "This is bigger than any single senator now. I am concerned that Trent has been weakened to the point that may jeopardise his ability to enact our agenda and speak to all Americans.

"There are several outstanding senators who are more than capable of effective leadership, and I hope we have an opportunity to choose.

Mr Lott said he intended to salute his friend Mr Thurmond

"Can he (Lott) be effective? Can he campaign in places like Chicago? I don't want to squander our ability to get things done."

But another senior Republican, Senator Mitch McConnell, said Mr Lott should be allowed to remain as leader.

"Senator Lott knows that he is weakened. He knows he made a bad mistake. But he has apologised... on four different occasions. I think we ought to accept the apology and move on."

Mr Lott made his controversial remarks at Mr Thurmond's 100th birthday celebration.

President George W Bush, in a rare rebuke, called Mr Lott's comments offensive and wrong.