WASHINGTON -- The tea party movement shows some growing pains, but it still wields remarkable powers to shape the Republican Party and set up a fall election with unconventional candidates and stark choices for voters.
In two high-profile primary elections Tuesday, establishment GOP candidates were stunned by come-from-behind winners backed by tea party activists and other conservatives who don't necessarily associate with that loose-knit group.
National Republican leaders are sifting through the results. Voter fervor on the right delights them, but some fear their insurgent nominees might stray too far from the mainstream to win in November.
In South Carolina's Republican gubernatorial primary, state Rep. Nikki Haley trailed a congressman, the lieutenant governor and attorney general for months. But a tea party surge and Sarah Palin's endorsement propelled her to an easy first-place finish. She faces Rep. Gresham Barrett in a June 22 runoff.
In Nevada, tea party favorite Sharron Angle overtook a better-known rival and won the right to challenge Senate Majority Leader Harry Reid in the fall. The outcome delighted Reid, who hopes to revive his re-election prospects by highlighting Angle's unorthodox views, such as privatizing Social Security and eliminating the federal Energy and Education departments.
The tea party is not invincible, of course. Relatively mainstream Republican candidates won the Senate and gubernatorial nominations in California. And conservatives' quarrels in a highly competitive House district in Virginia spelled doom for five candidates who claimed tea party ties.
A new Washington Post-ABC News poll found growing discontent with the tea party movement, with half of Americans saying they have an unfavorable impression of it.
But some conservatives see it as sign of maturity, with people paying more attention and recognizing the tea party's clout.
In South Carolina, Barrett, a four-term congressman, and two other GOP gubernatorial hopefuls were better known than Haley. In the primary's closing days, "the big difference was the tea party, the grass roots, the awakening you see across the country gravitated towards Nikki Haley," said Sen. Jim DeMint, R-S.C., a tea party champion. "That was pretty stunning."
The movement had another victory on Tuesday. In Maine, a tea party favorite, Waterville Mayor Paul LePage, won the GOP nomination for governor.
These events follow the stunning rejection of three-term Sen. Bob Bennett of Utah in a GOP convention, libertarian-conservative Rand Paul's victory over a Republican establishment favorite in Kentucky's Senate primary and Gov. Charlie Crist's forced withdrawal from Florida's GOP Senate primary.
Democratic voters have shown a similar but less virulent impatience with perceived compromisers. Republican-turned-Democratic Sen. Arlen Specter lost his renomination bid in Pennsylvania, but Lincoln narrowly survived in Arkansas.
In general, conservative activists are pushing the Republican Party to the right more than liberal activists are pushing the Democratic Party to the left, said Emory University political scientist Alan Abramowitz.
If either side pushes too far, however, it can end up with nominees unpalatable to centrist and unaffiliated voters who turn out in November but not in primaries.
"The base of the parties are looking for ideological purity. The middle is looking for effective leadership," said Sen. Lindsey Graham, R-S.C., who has angered some tea party activists by occasionally working with Democrats on issues such as climate change and immigration.
"The more you have to worry about being challenged by the base," he said, "the less likely you are to engage in solution politics that people are yearning for."
Democrats say that's precisely where the tea party movement is taking the GOP.
"Sharron Angle is focused on appealing to the fringe wing of her political party," said Sen. Bob Menendez, D-N.J., head of the Democratic Senatorial Campaign Committee.
The challenge for Republican officials in Nevada, Kentucky and elsewhere is to make peace with their non-establishment nominees and harness the right wing's fervor for the fall campaigns. The tea party is going away no time soon.