Santorum under fire in testy debate
Mesa, Arizona - Rivals piled criticism on US presidential candidate Rick Santorum at a testy debate on Wednesday, attempting to blunt his surprise surge at a pivotal period in the Republican race.
Santorum went through an uncomfortable two hours fending off criticism of his Senate record, in his first turn at centre stage after rising in polls in recent weeks.
Libertarian Congressman Ron Paul got in a zinger when asked why his campaign had run a television ad calling Santorum a fake. "Because he's a fake," Paul said bluntly.
Santorum, a former Pennsylvania senator, often complained earlier in the campaign that he was ignored by moderators in debates.
All eyes are now on the social conservative in a battle with long-term frontrunner Mitt Romney. They are competing fiercely for the Michigan and Arizona primaries on February 28 that will set the table for "Super Tuesday" on March 6 when 10 states vote.
Former Massachusetts governor Romney went after his chief rival often, accusing him of supporting "earmarks", the pet spending projects that members of Congress often slip into legislation.
Many Republicans would like to ban earmarks to help close the budget deficit.
Romney pointed out that Santorum had supported a much-derided $400m "bridge to nowhere" project in Alaska that was eventually abandoned. Santorum shot back that Romney had sought earmarks to pay for security at the 2002 Winter Olympics in Salt Lake City.
"When I was fighting for the Olympics, you were fighting for the 'bridge to nowhere'," Romney told Santorum.
"You don't know what you're talking about," Santorum snapped back.
The debate was the 21st of the 2012 election cycle for Republicans and possibly the last, giving the proceedings a dose of tension.
Tempers flared between Santorum and Romney and at one point the two candidates talked over each other, refusing to cede the floor. At times the crowd booed. Debate moderator John King of CNN frequently let the two candidates battle it out.
Santorum and Romney are in a close race in Michigan, according to opinion polls, with most recent surveys showing the two divided by four percentage points or fewer. A victory in Michigan is critical for Romney as he needs to prove he can win in the state where he was born.
The Republican candidates are vying for their party's nomination to challenge President Barack Obama, a Democrat, in a November 6 general election.