Minnesota rivals Tim Pawlenty and Michele Bachmann sparred bitterly Thursday night during an eight-candidate Republican debate, trying to break out of the GOP presidential pack ahead of an Iowa test vote with huge consequences.

Romney, who has emerged as the GOP's candidate to beat during his second presidential bid, was going into his first debate with his critics already telegraphing their eagerness to link the former Massachusetts governor with President Barack Obama's health care overhaul.

Hardly the start he'd hoped for, Newt Gingrich's first week as a presidential candidate has been riddled with missteps that have angered many of his fellow Republicans and exposed campaign vulnerabilities.

Republican presidential contender Newt Gingrich on Monday said Alzheimer's disease is on pace to cost the government some $20 trillion over the next four decades and said boosting federal research money would be a wise investment.