By Kevin Anderson BBC News Online, Washington

The vultures are circling.

Speculation has begun on who might replace Senator Trent Lott as the Republican leader in the US Senate.

Key members of his party have been calling for either his removal or, at the least, a conference to consider his future as majority leader.

Support from the White House for Senator Lott is beginning to falter, but he will not leave without a fight, which is just what some Republicans fear.

Presidential condemnation

The controversy has been building for almost two weeks now after Senator Lott made comments at the 100th birthday celebration for retiring Senator Strom Thurmond.

Senator Lott said the US would not have "all these problems" had it elected Mr Thurmond as president in 1948 when he ran as a staunch segregationist.

Any suggestion that the segregated past was acceptable or positive is offensive and it is wrong President Bush

Mr Thurmond said during his presidential campaign: "All the laws of Washington and all the bayonets of the army cannot force the negro into our homes, our schools, our churches."

The crisis for Mr Lott came to a head last week, when President George W Bush forcefully condemned his statements.

"Any suggestion that the segregated past was acceptable or positive is offensive and it is wrong," Mr Bush said.

The president did not call for Senator Lott to step down as Republican leader of the Senate, but now Mr Lott is faces challenges from within his party.

Challenge from within

The second-ranking Republican in the Senate, Don Nickles, has called for Mr Lott to go.

"Trent has been weakened to the point that may jeopardise his ability to enact our agenda and speak to all Americans," Senator Nickles said in a taped interview for US network ABC.

White House support for Mr Lott is fading

Mr Nickles has not said if he would seek Mr Lott's post, if it became available.

Mr Nickles must walk a fine line between pressing for Senator Lott's removal and being seen to pursue his own ambitions.

The White House stance? Condemnation and carefully measured silence.

White House spokesman Ari Fleischer called Mr Lott's comments "offensive and repugnant".

But in a change from earlier statements, he would not defend Mr Lott's position as Republican leader in the Senate, although given several opportunities during his daily news briefing.

"The White House isn't commenting on that. The White House doesn't comment on every idea, every motion," Mr Fleischer said.

Quick action encouraged

For the first time during the controversy, Mr Lott's position as Republican leader in the Senate is in jeopardy.

He is not taking the criticism lying down, making several public apologies and appearing on Black Entertainment Television to speak about diversity and economic opportunity.

His allies worked the phones over the weekend to try to shore up support for the embattled political leader.

Bowing to pressure from Republicans in the Senate, the party will hold a conference to discuss Mr Lott's future as leader.

The conference will be held 6 January, but some Republicans are pushing for an earlier meeting to settle the matter.

"And should we leave him dangling out there for another two weeks or so before we come back on the 7th? I say no. I don't think it's fair to the party," said Senator John Warner.