The Democrats who described the Obama campaign's approach to his fellow Illinois Democrat spoke on the condition of anonymity, saying they were not authorized to be quoted by name.
But when asked on the tarmac in Columbia, Mo., whether he had approached Mr. Emanuel to be his chief of staff, Mr. Obama demurred, saying: "I'm trying to win an election."
When a reporter from The Washington Times shouted, "Is that a no?" the candidate responded, "Plouffe is my chief of staff," referring to his campaign manager, David Plouffe.
On the plane earlier, Obama strategist David Axelrod warned reporters not to believe everything they read.
An aide to the congressman, Sarah Feinberg, said in an e-mail that Mr. Emanuel "has not been contacted to take a job in an administration that does not yet exist. Everyone is focused on Election Day, as they should be."
Mr. Emanuel is a veteran of President Clinton's White House and has made a rapid ascent of the House leadership ladder since his election to Congress in 2002. He was chairman of the Democratic Congressional Campaign Committee two years ago when the party won a majority for the first time in more than a decade, and he cemented his reputation as a prodigious fundraiser and strong-willed political strategist.
Both Mr. Obama and Republican presidential candidate John McCain have authorized their staffs to begin transition operations in recent weeks.
Even so, Republicans seized on the disclosure.
"Emanuel is among the most vitriolic and partisan people in American politics," said Alex Conant, a Republican National Committee spokesman. "Reports that Obama wants him to be White House chief of staff undercut any claims to unity and bipartisanship and should alarm every voter."