Some of the most potent examples of Tea Party power in the 2010 and 2012 election cycles were the taking down of establishment Republican Party Senate candidates; think Marco Rubio, Christine O'Donnell, Ted Cruz, and Todd Akin. But those candidates met with mixed success in the general elections and heading into the 2014 cycle, the Tea Party may have a new path to relevance while the Republican Party aims to win control of the Senate.
Though it's still early, there are no standout, truly anti-establishment candidates threatening any of the top incumbent Senate Republicans, though there are races in conservative strongholds such as South Carolina, Texas, Oklahoma, Kentucky, and West Virginia.
"It's possible those people will emerge, but it's also possible that 2012 might give the establishment a little bit more power," says Kyle Kondik, political analyst at the University of Virginia's Center for Politics. "These incumbents are sort of battening down the hatches and have been for months, if not years as they've seen some of their colleagues get in trouble."
Even in states that are likely to boast a Tea Party-approved standard bearer, such as Rep. Steve King in Iowa, they aren't true usurper candidates.
"He seems a lot more in control of his own image than say, Todd Akin," Kondik says. He adds that though King could win a statewide race, if Republicans' goal is to win the seat, "King is not their best nominee."
Where new voters were pulled into the political process based on dissatisfaction with President Barack Obama, and specifically his 2010 healthcare law, and rampant federal spending amid a floundering economy, and were able to shock GOP incumbents in states from Arizona to Florida to Delaware, the element of surprise and level of passion has dissipated since.
"The enemy in 2010 was as much Republicans as it was Democrats. They didn't like Obamacare and the overspending, but they also felt many of the Republicans had participated in that," says David Woodard, a professor at Clemson University and GOP consultant. "The sense I have now is that it's 'Us versus The Democrats.'"
Woodard says incumbents like South Carolina Sen. Lindsey Graham, a Republican long thought to be vulnerable to a Tea Party challenge, have wised up to conservative concerns and worked to build ties with critics.
"Lindsey Graham will mend fences with anybody," Woodard says, noting the incumbent senator sought out meetings with local Tea Party officials who cast votes of 'no confidence' against him to help bolster his chances of re-election.
"They're still a potent part of the Republican Party, but I just don't think that they're going to pick some of these isolated candidates [to back]; certainly the fact that these establishment politicians have begun to take note of Tea Party people shows their power," Woodard says.
Even places that boasted strong Tea Party performances in the past, such as Alaska, are less and less likely to proffer similar performances. In 2010, Tea Party candidate Joe Miller beat out incumbent Sen. Lisa Murkowski in the Republican primary, but Murkowski was able to retain her seat though a write-in effort. So even though Democratic Sen. Mark Begich is up for re-election and Miller's name has been tossed around as a possible rival, Kondik says he won't likely emerge as a force again.
"I would be kind of surprised on that one; I think he's kind of a stale candidate at this point given how poorly he ended up doing in 2010," he says.
In West Virginia, Republicans are aiming to pick up a seat thanks to the retirement of Democratic Sen. Jay Rockefeller. But it's sitting GOP Rep. Shelley Moore Capito, the most mainstream and well-established Republican in the state who is the frontrunner for her party's nod, despite the state party's very conservative reputation.