If the political universe unfolds as Republicans believe it should, the party will wrest control of the U.S. Senate in next year's mid-term elections, setting the stage for winning the White House in 2016.
Math and the big political picture seem to favour the party. Of the 35 Senate seats in play next year, 21 are held by Democrats, and only 14 by Republicans. And seven of those Democrat-held seats are in states won by Republican presidential hopeful Mitt Romney in 2012. Only one of the at-stake Republican Senate seats is in a state won by President Barack Obama.
But looming Tea Party challenges to sitting Republicans could undermine the party's hopes of picking up the six seats it needs in the 100-seat Senate to regain the majority it last held in 2007. In some solidly Republican states, that may not matter because the party will likely retain the Senate seat irrespective of the candidate. In other, less-red states, a Tea Party primary triumph could be a Pyrrhic victory and deliver the seat to the Democrats. It happened in 2012 in Indiana.
There, Richard Lugar, a six-term Republican senator and one of Washington's most influential lawmakers, especially on foreign policy, lost a primary challenge to Tea Party activist Richard Mourdock. But Mr. Mourdock's right-wing views extended to saying that if a raped woman became pregnant it was "something that God intended to happen." On election night, Democrat Joe Donnelly won handily, the first Democrat to win a Senate seat in Indiana for more than two decades.
For some Republicans, that's a nightmare that could recur.
In South Carolina, Republican Sen. Lindsey Graham, a respected moderate with a long record of bipartisanship, would have little trouble winning re-election. Three years ago, he predicted the Tea Party "would die out." Instead, Mr. Graham faces four primary challengers and unless he can win 50 per cent in the first round, a run-off next June.
At least seven other Republican incumbents face primary challenges from right-wing insurgents seeking to wrest control of the party.
In Kentucky, Sen. Mitch McConnell, the party's leader in the Senate, is being challenged by Tea Party activist Matt Bevin. While polls show Mr. McConnell ahead, he is not as confident as he might be. His campaign has already launched attack ads against Mr. Bevin.
In Mississippi, 76-year-old Sen. Thad Cochran, is facing the toughest fight of his political life after 40 unbroken years in Congress. The second-most-senior Republican senator wants a seventh term but is being challenged by Chris McDaniel, 41, another Tea Party hopeful who denounced this week's bipartisan budget deal and has built a formidable war chest.
Former vice-president Dick Cheney's daughter Liz won't call herself a Tea Party candidate. Still, she basks in their support and says, "They've really sent a message that the people we elect need to make sure they remember that they work for the people who sent them to Washington." Ms. Cheney is challenging Sen. Mike Enzi, the 69-year-old Republican first elected to the Senate for Wyoming in 1996. "It's time for a new generation of leaders in Washington," says the 47-year-old Ms. Cheney.
Even staunchly conservative Republicans like Texas Sen. John Cornyn face insurgent challenges. Steve Stockman, another Tea Party darling, who once accused the Clinton administration of staging the fiery raid on cultists in Waco to justify an assault-weapons ban, filed his bid to unseat Mr. Cornyn minutes before the deadline on Monday. Mr. Stockman has also called for Mr. Obama's impeachment and for the U.S. to pull out of the United Nations. Few give his challenge much hope.
But even long-shot challenges divert resources party strategists want to save for battling the Democrats.
"Most of us are preparing for campaigns from Republicans instead of Democrats," said veteran Tennessee Republican Sen. Lamar Alexander, who is also facing a Tea Party challenge. "We have an unprecedented opportunity to capture the Senate in 2014 and lay the groundwork for capturing the presidency," he told the website Politico. "I would think all this effort and money that's going into running against incumbent Republicans would be better directed towards defeating incumbent Democrats."