Tea party activists have been saying all along that their movement is about something more than winning elections. And as the bloody Republican primary season reaches an end, they have proved they really mean it.

Their parting shot at the Republican establishment was their loudest.

In defeating the GOP’s strong prospect for picking up a Senate seat in Delaware — and thereby dampening its chances of regaining a Senate majority — the tea party has delivered a clear message to the Republican establishment: You are not in charge.

“This is about changing the system,” Christine O’Donnell, the tea party pick, said Tuesday night as she celebrated her stunning primary victory over Rep. Michael Castle.

Her upset was the biggest in a string of tea party victories this season over establishment-backed candidates in Alaska, Colorado, Kentucky, New York and Utah.

The end of the primaries normally is a time when parties try to close ranks, but O’Donnell’s win fueled another spasm of recriminations.

After GOP strategist Karl Rove said Tuesday that O’Donnell was unelectable — echoing the assessment of, among others, Delaware Republican Party Chairman Tom Ross — he came under fire from a battalion of conservative commentators.

“I’ve never heard Karl so animated against a Democrat as he was against Christine O’Donnell last night,” said Rush Limbaugh, whose radio show Rove had recently guest-hosted.

Meanwhile, the victorious candidate used a round of television interviews to blast a GOP establishment that she said was lazy and guilty of “political cannibalism” in its efforts to defeat her.

The National Republican Senatorial Committee, which had been silent about her win except for a tepid statement by Executive Director Rob Jesmer, quickly announced that it would be sending her a check for $42,000, the maximum allowable under the law.

In a statement, the NRSC’s chairman, Sen. John Cornyn, R-Tex., said: “Let there be no mistake: The National Republican Senatorial Committee — and I personally as the committee’s chairman — strongly stand by all of our Republican nominees, including Christine O’Donnell in Delaware.”

O’Donnell’s victory was not the only big surprise on Tuesday night.

In New York, newcomer Carl Paladino, a businessman backed by tea party groups, soundly defeated former congressman Rick Lazio, who had been considered the favorite until the final stretch of the race.

The GOP hierarchy did claim a win in New Hampshire, however, where former attorney general Kelly Ayotte beat lawyer Ovide Lamontagne, who had tea party support. But Ayotte — like O’Donnell — had also been helped by the backing of former Alaska Gov. Sarah Palin and other leading conservatives.

O’Donnell’s victory marks the fourth time this year that the tea party has been blamed for — or credited with, depending on the point of view — forcing the Republicans to put the ideologically purer Senate candidate on the ballot in November, rather than the one who has the greater chance of winning.

But the three others — Ken Buck in Colorado, Sharron Angle in Nevada and Rand Paul in Kentucky — have proved to be stronger than Republican naysayers predicted.

Although the tea party may have cost Republicans their best shot at winning some key races, party leaders insist that the anti-establishment anger it represents and channels will benefit the GOP in November.

“We’re in the eye of the storm here,” said Don Stewart, a spokesman for Senate Minority Leader Mitch McConnell, R-Ky. “Those people are fired up, and they are not going to vote Democrat. We are about to hit the other side of that storm.”

But even after the midterm elections, establishing peaceful coexistence within the GOP ranks may be no small challenge — not least because some tea party candidates are promising to do the opposite.

“Republicans have been a big part of the problem. I’m not going to Washington, D.C., to fit in with big-spending Republicans,” said Buck, in an interview in July before he won the Senate nomination.

Tea party candidates bristled when former Senate GOP leader Trent Lott, Miss., now a lobbyist, told The Washington Post in July: “As soon as they get here, we need to co-opt them.”

They argue that the rise of their movement will in fact make other Republicans less inclined toward compromise and accommodation.

Whether or not the party wins control of either house of Congress this fall, every Republican lawmaker will be keenly aware of incumbents who fell in the primaries because they were insufficiently conservative. They will know that in the era of the tea party, any step away from the path of orthodoxy could be the making of a devastating campaign ad — or a primary opponent.

“That’s going to make people very nervous about their votes,” said former Rep. Vin Weber, R-Minn., who is now a lobbyist.

Particularly on spending, “the safest vote politically will be no,” he added — which means it could be difficult for Republican congressional leaders to marshal the numbers they need even for routine appropriations bills that are necessary to keep the government operating.

With such a strong political force at work within the party, Republican congressional leaders may also have to look over their own shoulders.

Former House Majority Leader Dick Armey, R-Tex., whose Freedom Works organization has helped organize tea party events, predicted on CNN earlier this month that the movement could force the kind of cultural shift that the Republican “Class of 1992” made in the House two years before the GOP won back the chamber.

One of the first effects of that shift was the nudging aside of the congenial longtime House Republican leader Bob Michel of Illinois, in favor of firebrand back-bencher Newt Gingrich of Georgia.

The tea party phenomenon may also have the effect of getting the 2012 Republican presidential race off to an earlier start, and sending the contenders further to the right.

Led by Palin, the potential candidates have been unusually active in contentious primary contests, which in some instances have become proxy wars.

On Wednesday, former Massachusetts Gov. Mitt Romney, who is expected to make another bid for the White House in 2012, announced his endorsement of O’Donnell and gave her $5,000.

“Now is the time for Republicans to rally behind their nominee, Christine O’Donnell,” he said. “She ran an impressive campaign. I believe it is important we support her so we can win back the U.S. Senate.”


Washington Post Staff Writer Dan Balz contributed to this report.