The Tea Party's first official win came when Rand Paul, whose libertarian beliefs include challenging 1960s civil-rights laws, captured Kentucky's Senate seat. Next it was Marco Rubio, another darling of the movement, who pulled off a stunning win to secure Florida's.
But long before any of the ballots were cast in this midterm election, the Tea Party could rightly claim victory.
Less than two years after bursting onto the scene to protest against U.S. President Barack Obama's economic-stimulus package, the Tea Party movement has succeeded in transforming itself from a disparate collection of grassroots anti-government forces into a potent political force to be reckoned with in Washington.
"I don't think there's any question of that," said Burdett Loomis, a professor of political science at the University of Kansas.
"They have defined the debate. They have succeeded in backing candidates who've sprung some pretty significant upsets."
At his victory party in Bowling Green, Ky., Mr. Paul told cheering supporters: "Tonight there's a Tea Party tidal wave!"
Mr. Paul and Mr. Rubio's high-profile victories for the Tea Party gave the Senate a rightward jolt. In South Carolina, Nikki Haley, a Tea Party-backed Republican lawmaker, became the state's first female governor.
Republicans profited more widely from a wave of popular sympathy for the movement, with four in 10 voters at exit polls expressing support for it.
The Tea Party had already played a significant role, win or lose, in several crucial primary fights. Candidates backed by Tea Party figures who won Senate nominations included Christine O'Donnell of Delaware, who defeated Representative Michael Castle in Delaware but ultimately lost her Senate race. The Tea Party also recalibrated the primary race in Alaska, where Joe Miller beat Senator Lisa Murkowski, the incumbent, for the Republican nomination.
Now, with a critical mass of loyalists bound for Capitol Hill, the Tea Party movement is poised to evolve from a protest movement into one wielding real political power.
"The question is, what does that mean?" Prof. Loomis asked.
Observers say the diffuse nature of the movement will make it a tough fit in government. Most of the candidates backed by Tea Party figures ran under the Republican Party banner, even though some fundamentally disagree with the party's policies.
While former Alaska governor Sarah Palin is seen by many as the self-anointed queen of the Tea Party, the movement has no elected leader, national committee or even a website. Instead, a handful of different groups, from Tea Party Express to Tea Party Patriots, claim to speak for the movement.
"It's not like saying you sell McDonald's hamburgers. It's not an exclusive franchise," said Ross Baker, a professor of political science at Rutgers University.
"Who exactly is the enforcer of Tea Party theory and discipline? There isn't anybody."
Still, he says the real implications of the rise of the Tea Party movement have yet to be felt.
"The real effect is going to be once the Republicans organize themselves in Congress and sort out exactly how much influence the Tea Party-sponsored candidates are going to have," he explained.
Prof. Baker says there are only two real options: "One is that they will be co-opted because they will be out of their depth and unable to navigate the complexities of the Hill. The other is that they will serve as an insurgency."
On that issue, analysts are divided.
Some say the Tea Party will be emboldened by its success in the midterm elections, and that the Republicans will be hard-pressed to contain them.
Others say the movement will fizzle because it will prove incapable of offering a coherent alternative to President Obama's strategies, however unpopular or misunderstood.
Wendy Schiller, a professor of political science at Brown University, argues the Tea Party's protest rhetoric won't translate into policy.
"Cheap talk isn't going to be good enough. They're going to have to accomplish something they promised Tea Party voters … cutting federal spending and cutting taxes," she said.
In the end, the Tea Party's fate may lie largely in the hands of the Republican Party itself, which won back the House of Representatives but must now contend with a new brand of dissension within its ranks.
"For the Republicans to be successful, they need to incorporate the Tea Party into their fold to avoid a direct challenge in 2012," Prof. Schiller argued.
Virtually everyone agrees the Tea Party, once dismissed by political pundits as a passing fad, will have an enormous impact in Washington in the coming months, if not years.
Prof. Loomis predicts the political pendulum will eventually equalize because the Republicans will "try to pull the Tea Party back" as a means of self-preservation and because "the trend in American politics has always been back towards the centre."
"Maybe now the centre ends up being somewhere different than it was before," he added.