"While he may have managed to win the Michigan and Arizona Republican primaries, tonight's victories have come at a great cost for Mitt Romney — he has moved far to the right in an obvious effort to pick up support from extreme Tea Party voters," Democratic National Committee Chairwoman Debbie Wasserman Schultz said in a statement while Romney spoke.
Party elders and elites had shown signs of worry that Romney was taking so long to win the primary. A top GOP senator told ABC News that if Romney didn't win in Michigan, "we need a new candidate."
Analysts have speculated on a number of popular figures in the party, including Chris Christie, Sarah Palin, Mitch Daniels and even Jeb Bush, but all of them have said they're not interested in running for president, at least this year.
As Michigan residents voted on Tuesday, Romney said in an interview on Fox News that he doesn't think the nominating process would be so contested that it leads to a brokered convention after the states have finished voting.
"That's just not going to happen," he said.
The eve of the Michigan primary, some Democrats unearthed a plan to tip the vote to Santorum by voting in Michigan's open system for the right-wing candidate, seeking to prolong Romney's journey to clinch the nomination.
With nearly every poll putting Romney and Santorum even, Democrats -- mainly a campaign consultant in Michigan and a liberal blogger -- hoped that just a few thousand votes would crown Santorum the winner. Exit polls found that one in 10 voters said they were Democrats.
According to those polls, 53 percent of the Democrats who voted in the Republican primary in Michigan picked Santorum, while 17 percent of them chose Romney.
Democrats and Santorum's campaign were calling Michigan a defeat for Romney days before the vote, based on his advantages -- chiefly that he was born and went to high school there and that his father was a popular governor.
The evening was also coupled with another loss for Republican moderates: the retirement announcement of Sen. Olympia Snowe, who said in a statement that she was quitting because she was frustrated "that an atmosphere of polarization and 'my way or the highway' ideologies has become pervasive in campaigns and in our governing institutions."