Democratic hopeful Barack Obama won the endorsement of former rival Chris Dodd as Hillary Clinton looked to an evening debate to shake up a US presidential race tilting against her.
On the Republican side, presumptive nominee John McCain was
forced to apologise in Cincinnati after Bill Cunningham, a
conservative radio talk show host who preceded him at a rally,
three times referred to Obama as "Barack Hussein Obama."
Cunningham also said a Clinton backer, former Secretary of State Madeline Albright, "looks like death warmed over."
"I want to disassociate myself from any disparaging remarks that were made," McCain told reporters. He said he did not select Cunningham to appear at the rally and had never met him.
Obama's full name is Barack Hussein Obama but for a critic to mention his middle name suggests an attempt to associate him with the late Iraqi leader Saddam Hussein.
Dodd, a veteran Connecticut senator who dropped out of the campaign for the Democratic presidential nomination in early January, announced his support for Obama at a news conference with the Illinois senator.
Dodd said he had been "skeptical like many others" of Obama but had been won over and felt now was "a moment of unity in our country" when Democrats need to rally behind him.
Obama and Clinton were to face off in a debate in snowy Cleveland, Clinton's last big chance to turn around the race ahead of potentially pivotal contests next Tuesday in Texas and Ohio, two states where polls show Obama making a move.
A New York Times/CBS News poll said Obama is now viewed by most Democrats as the candidate best able to beat the presumptive Republican nominee John McCain, in the November election to determine President George Bush's successor.
The good news for Obama came amid signs of frustration in the struggling campaign of Clinton, once considered the odds-on favorite to win the Democratic nomination and now in danger of getting knocked out of the race.
The Washington Post has reported that over a breakfast meeting with a group of reporters on Monday, Clinton press secretary Phil Singer chided journalists for "woefully inadequate" coverage of Obama.
At the same breakfast, Clinton senior adviser Harold Ickes told the group: "I think if we lose in Texas and Ohio, Mrs. Clinton will have to make her decisions as to whether she goes forward or not."
Washington pundits over the past couple of days have wondered aloud which Clinton will show up at the Cleveland debate, the one who last week in Texas said she was honored to share the debate stage with Obama, or the one who on Saturday declared, "Shame on you, Barack Obama," for what she basically said was lying about her record.
Obama said at the news conference with Dodd that the race "has gotten a little hotter over the last couple of days" and that he had told his staff - and hoped Clinton had told hers - "let's make sure that we maintain the kind of campaign that, win or lose, we will be proud of afterwards."
Clinton admitted at a town-hall meeting in Lorain, Ohio, that "I got a little hot over the weekend" about the Obama campaign. In talking about turning around the US economy, she again criticised Obama's reliance on speeches long on inspiration but lacking a lot of substance.
"I can't do it just by hoping for it. Hope is not a plan," Clinton said.
Clinton has been trying to raise questions about whether Americans should risk handing the presidency to Obama at a time of global turmoil, given his relative inexperience as a first-term senator.
The New York Times/CBS News poll suggested this line of attack was not working.
It said 47% of registered voters had confidence that Obama would deal wisely with an international crisis, compared to 39% who had confidence in Clinton. And the poll said 69% believed Obama would be an effective commander-in-chief, compared to 54% for Clinton.