But the movement's appeal, while growing, has yet to be tested fully, as evident in this week's runoff election in Alabama where Tea Party favorite Rick Barber lost to Martha Roby. Despite his grassroots campaign and controversial ads depicting the founding fathers, Barber lost the race for an Alabama congressional seat to a candidate favored by the Republican establishment.
The Tea Party remains fragmented, there's no one unified voice or group representing the movement, and it doesn't enjoy the status of an official party. While most of its members associate with the Republican party, many of their beliefs are at odds with the GOP.
Yet Tea Party fervor has spread from coast to coast, with grassroots momentum reminiscent of President Obama's own boots-on-the-ground strategy that propelled him to victory in 2008.
Several high-profile candidates who have closely attached themselves to Tea Party ideology have gained national recognition, such as Kentucky's GOP Senate candidate Rand Paul, Nevada's Republican Senate challenger Sharron Angle, South Carolina gubernatorial candidate Nikki Haley, and Utah Senate nominee Mike Lee.
The Tea Party's efforts were also vital in driving out Republican Sen. Bob Bennett, the three-term senator from Utah who lost his re-election bid.
At the same time, just as many Tea Party favorites have failed to secure key nominations -- California Senate hopeful Chuck DeVore lost to businesswoman Carly Fiorina; Doug Hoffman lost in the New York House special election despite Sarah Palin's backing; and Idaho Congressional candidate Vaughn Ward lost the Republican primary even though he nabbed Palin's endorsement.
Tea Party candidates such as Barber and Angle were embroiled in tense competitions within their own parties. And some Republicans have voiced concerns that the Tea Party-fueled momentum will only inadvertently hurt the GOP.
"With the Tea Party creating the mischief that it is in Colorado, we may not win that seat. My sources in Nevada say with Sharron Angle there's no way [Senate Majority Leader] Harry Reid loses in Nevada," Bennett said in an interview with The Associated Press last week. "At the moment there is not a cohesive Republican strategy of this is what we're going to do. And certainly among the Tea Party types there's clearly no strategy of this is what we're going to do."
But Tea Party supporters say the discord in the movement is its strength, not a weakness.
"It's designed to be fragmented. That's the difference between the Tea Party and the political elite," said Shelby Blakely, a spokeswoman for Tea Party Patriots, a national group that provides support to local Tea Party organizations.
The differences of opinion are "mathematically impossible to avoid and we actually don't want to," Blakely said. "We are working towards a common goal and when it comes down to the wire, we unite and we become a rather larger force of people who can donate millions of man hours and resources to the right candidates, to the right issue, the right legislation. We've proven that."
Harvard historian and New Yorker writer Jill Lepore said the Tea Party's mixed results in the primaries speak to the current disequilibrium in U.S. politics.
"I actually think it's not a political movement and I think it's important to recognize that," said Lepore, whose book, "The Whites of Their Eyes: The Tea Party's Revolution and the Battle over American History," will be released in October. "People subscribe to it essentially because of beliefs, not so much ideas but beliefs -- about the nature of the world and about the relationship between the past, the present and the future. ... In many ways it defies description."
Tea Party Tested in Primaries
Many candidates are exploiting the popular grassroots momentum of the Tea Party, but it's too early to tell how long that allegiance will remain.
In Massachusetts, the Tea Party helped Sen. Scott Brown win an upset victory over Democrat Martha Coakley for the late Sen. Ted Kennedy's Senate seat. The Tea Party Express released an ad extolling the virtues of Brown, and the Our Country Deserves Better PAC poured money into his campaign. He was hailed by many as the first official Tea Party victory, even though Brown distanced himself from the movement.
But Brown's decision to side with the Democrats on Wall Street reform outraged Tea Party members, leading many to call him a traitor. The Greater Boston Tea Party said in a statement Brown "defied" his commitment to activists and his donors, and questioned whether the group will support him in 2012 for re-election.
"I think that we are going to make huge gains. I believe we will then continue to hold responsible those people who get elected using Tea Party help," Blakely said. "If these candidates want to continue to be elected they are going to have to adhere to the core values of the Tea Party, specifically constitutionally limited government and fiscal responsibility."
Americans' view toward the Tea Party is divided. In an ABC News/Washington Post poll released this week, 30 percent said they are more likely to support a candidate who is associated with the Tea Party political movement, while 30 percent said they are less likely to do so.
Another ABC News/Washington Post poll released in May found that 27 percent of Americans supported the Tea Party but nearly as many oppose it.
Despite the lack of direction and an clarity on how the Tea Party will fare in November, the movement's advocates are confident their influence will only expand.
"I believe it is the preeminent formidable force," Blakely said.
Lepore said it's difficult to predict what the future holds for the movement, and it's difficult to tell right now whether their favorite candidates are electable, but the upcoming elections will be a major test of the Tea Party's appeal.
"I think it's a moment in time that involves a lot of passion and large numbers of people are accepting it," Lepore said. "Until we get through this moment of equilibrium, it will be a little bit hard to predict."
The next test of Tea Party's mettle is in Georgia, where on July 20, Palin-endorsed Karen Handel will face off against former Rep. Nathan Deal for the Republican gubernatorial nomination.