WASHINGTON - UNITED States President-elect Barack Obama has not even stepped into office and already a scandal, not of his own making, is threatening to dog him.

Mr Obama is accused of nothing. But that his fellow Democrat and Illinois Governor Rod Blagojevich has been charged with trying to sell Mr Obama's now-vacant US Senate seat gives political opponents an opening to criticise him.

Since Blagojevich's arrest on Tuesday, Mr Obama has been pointedly distancing himself from the case.

He took another step back on Wednesday by joining others demanding the governor's resignation. A day earlier, he said: 'I had no contact with the governor or his office, and so I was not aware of what was happening' concerning any possible dealing about Blagojevich's appointment of a successor.

In an interview published in the Chicago Tribune and the Los Angeles Times, Mr Obama reiterated that point though he would not answer a question on whether he was aware of any conversations between the governor and his top aides, including incoming White House chief of staff Rahm Emanuel.

Blagojevich is accused of conspiring to sell or trade the vacant Senate seat for personal benefits for himself and his wife, Patti. Among his alleged desires: a Cabinet post, placement at a private foundation in a significant position, campaign contributions or an ambassadorship.

On Tuesday, US Attorney Patrick Fitzgerald said prosecutors were making no allegations that Mr Obama was aware of any scheming. Blagojevich himself, in taped conversations cited by prosecutors, suggested Mr Obama would not be helpful to him. Despite all that, there were signs the continuing investigation could still involve Mr Obama.

It appears that his friend, Ms Valerie Jarrett, an incoming senior White House adviser, is the person referred to repeatedly in court documents as 'Candidate 1'. That individual is described as a woman who is 'an adviser to the President-elect' and the person Mr Obama wanted appointed to the Senate seat. Court papers say Candidate 1 eventually removed herself from consideration.

Blagojevich talked at length about Candidate 1 in a Nov 11 phone conversation with an aide. A day later, Ms Jarrett, one of three co-chairmen of Mr Obama's transition team and a high-level adviser to his presidential campaign, made it known she was not interested. On Nov 15, Mr Obama announced that Ms Jarrett would be a senior White House adviser and assistant for inter-governmental relations.

On Wednesday, US congressman Jesse Jackson Jr, son of civil rights leader the Reverend Jesse Jackson, said at a news conference in Washington that he was 'Senate Candidate 5' in the government's criminal complaint - a man Blagojevich was secretly recorded as saying might be willing to pay cash for appointment to Mr Obama's vacant seat. The criminal complaint quotes the governor saying that an emissary from Candidate 5 had offered to raise US$500,000 (S$751,150) for his campaign treasury.

At the news conference, Mr Jackson said that 'I never sent a message or an emissary' and that he had not engaged 'whatsoever in any wrongdoing'.

Although Mr Obama's circle of major Illinois political allies and supporters is largely separate from Blagojevich's, there are some exceptions.

At least one top aide to Mr Obama, Mr Michael Strautmanis, previously worked for Blagojevich.

Many people in the court documents are referred to by aliases; there is little doubt their identities will eventually surface.

ASSOCIATED PRESS