WASHINGTON — It dominated the country's politics just two years ago, a grassroots rebellion that rolled through the Republican Party, helped seize power in Washington and threatened to upend the established order for years to come.

Now, the tea party is not what it was. As the Republicans wrap up their quest for a 2012 presidential nominee, their choice of Mitt Romney over Rick Santorum signals a shift back to a more traditional approach.

Romney's victory, sealed with Santorum's decision Tuesday to suspend his challenge, was a triumph of political pragmatism over ideology, a cool calculation by primary voters and the party establishment that the most important thing was picking someone who could win, not necessarily someone who should win.

In so doing, they set aside some of the passions that roiled the party just two years ago. Fed by a backlash against President Barack Obama and the Democratic Congress, those passions helped seize the House of Representatives. But they also led the party to purge moderates in states such as Colorado, Delaware and Nevada who could have won Democratic seats in the Senate.

Fresh from 2010, many Republicans raced into the campaign for the 2012 nomination thinking it was a natural extension of tea party politics.

Rep. Michele Bachmann of Minnesota proclaimed herself the chair of a tea party caucus in Congress, seized TV airtime to give a tea party response to Obama's State of the Union address, and then sought the nomination to challenge him. She boasted of her opposition to raising the nation's debt ceiling last year even if that forced immediate, deep cuts in spending.

She faded before the first votes were cast.

Others followed in search of the tea party label, one of social and economic conservative purity, unsullied by Washington insider status and unmatched by Romney, whose record of past support for health care mandates and abortion rights, they said, made him untrustworthy no matter what he said now.

Rick Perry, Herman Cain, Newt Gingrich, Santorum. All eventually waned.

In Wisconsin, site of the last primary and the contest that finally broke Santorum, Bonnie Adkins of Mukwonago summed up the feelings of a lot of Republican voters.

Drawn to Santorum by emotion — "He spoke from the heart" — she turned to Romney as she grew more pragmatic. "My number one priority is to defeat Obama. The big O's got to go," she said. "Romney has the better chance."

Lee Miringoff, director of the Marist Institute for Public Opinion at Marist College in New York, said, "There was an element of the Republican Party electorate where pragmatism became paramount."

That was particularly true this year given Republican desire to defeat Obama. Republicans might have been more open to taking a general election chance on a candidate more aligned with the tea party if the seat open had no Democratic incumbent running,

But the movement also has faded.

Take the early caucuses and primaries. Given the 2010 results, Republicans hoped the spillover would mean a surge of new tea party voters jumping at the chance to pick a conservative nominee to take on Obama. Instead, turnout in early caucuses and primaries was weak.

Tea party supporters did vote, but they were not first-time participants. They were, said Miringoff, "rebranded Republicans."

At the same time, the label turned as much into a warning as a boast.

Wisconsin was a telling study of the fate of tea party politics.

Backed by the tea party, Republican Scott Walker won the governor's seat in 2010. He challenged public employee unions in a budget fight last year and now faces a statewide recall vote in June. Polls suggest it will be close.

Republicans support Walker. But their embrace of the tea party is lukewarm. On primary day last week, 56 percent of voters said they supported the movement, according to exit polls. Another 25 percent were neutral, and 17 percent of Republican primary voters opposed it.

Nationally, the numbers are worse. A recent Fox News Poll found 30 percent of registered voters had a favorable opinion of the movement, down from 35 percent in 2010. At the same time, 51 percent had an unfavorable opinion, up sharply from 22 percent in 2010.

Ultimately, the tea party may have seen its peak in 2010, particularly in the glare of the media.

"They were never the dominant component of the Republican coalition, now or in 2010," said Republican pollster Whit Ayres. "They tended to do better in low-turnout primaries or in states dominated by conventions. That doesn't mean they were unimportant. They remain important, but they are not a dominant source in the party."

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