Embattled US Republican Senate leader Trent Lott is fighting for his political life after being challenged for his post by a fellow senator.

I'm pleased to join the Bill Frist team, and I can assure you the team is growing in numbers very quickly Senator John Warner

Senator Bill Frist of Tennessee - seen as a close ally of President George W Bush - said several senators had approached him, asking to seek the job.

Mr Lott, 61, has been under heavy pressure from several senior Republican senators to leave his post after making comments considered racist two weeks ago.

His fate is likely to be decided at a meeting of the party's 51 senators on 6 January, most of whom have made no public statements on the issue.

The White House said it would work with Mr Lott or any other leader elected to head the Republicans in the Senate.

Mr Bush took the unusual step of rebuking his Republican colleague Mr Lott for saying the US would have been a better place if Strom Thurmond had been elected president in 1948 on a segregationist platform.

Correspondents add that Mr Frist would be the likely White House favourite if an election is called.

Powerful support

Mr Frist - a 50-year-old physician from Tennessee - said in a statement of Thursday that several of his "colleagues in the Republican caucus... said they would like to support me for majority leader".

Mr Frist is said to have influential backers

"I indicated to them that if it is clear that a majority of the Republican caucus believes a change in leadership would benefit the institution of the United States Senate, I will likely step forward for that role."

So far, at least seven Republican senators have publicly stated that they would support Mr Frist.

Among them are such powerful figures as Senator John Warner, incoming chairman of the Armed Services Committee, and Senator George Allen, who will head the Republicans' Senate campaign in 2004.

"I'm pleased to join the Bill Frist team, and I can assure you the team is growing in numbers very quickly," Mr Warner told reporters.

Earlier, Senator Don Nickles - Mr Lott's Senate deputy - said there were other senators who would make more effective leaders than Mr Lott.

Mr Lott - who has apologised repeatedly for his comments at Senator Thurmond's 100th birthday party - has made no public statement on the leadership battle, but his spokesman said the senator had no plans to leave his post.

Mr Bush called Mr Lott's comments offensive and wrong

"Trent Lott will be the majority leader," the spokesman, Ron Bonjean, said.

"He has a track record of loyalty, dedication and experience in shepherding President Bush's agenda for all Americans through the Senate."

Mr Lott told Black Entertainment Television (BET) that, although he had supported segregationist policies in his home state of Mississippi in the past, he believed he had changed.