As more primaries near, Republican leaders appear to be justifiably confident that they've kept far-right candidates from sinking their chances of retaking the Senate in November. Which simply means that the simmering conflict between the establishment and the Tea Partiers will need to wait until the GOP is in power.

The failure of the Republican Party to make significant gains in the Senate in 2010 and 2012 is legendary by now. Candidates like Todd Akin, Sharron Angle, Christine O'Donnell, and Richard Mourdock proved adept at energizing the staunch conservatives that come out to vote in primaries, but were all beaten by Democrats in November. Last November, the Senate Republican campaign arm pledged to get involved in primaries specifically to avoid having Tea Partiers run rampant; the Chamber of Commerce pledged millions with the same aim.

That strategy appears to have worked. In addition to dumping money in support of more moderate candidates, the party has also "used quiet persuasion to smooth the way for their preferred candidates in pursuit of the net gain of six seats they need to win Senate control," Gerald Seib writes at The Wall Street Journal. "They say they opened up early channels of communication with tea-party groups and their financial backers to persuade them they can live with establishment favorites in some key states. Tea-party challengers remain there, but they lack oomph."

Among the most critical states for the Republicans are West Virginia, Louisiana, North Carolina, Alaska, Arkansas, and Georgia. In none of those states is there any robust Tea Party challenger to the establishment's preferred candidate. Which doesn't necessarily mean that one won't emerge or win — politics can be fickle — but it's a very different situation than in the past two cycles.

That success in cultivating palatable general election candidates is one reason that the Republicans seem poised to retake the Senate; 538 gives them a 50.8 percent chance of retaking the body. Which would mean that the Senate could be controlled by Mitch McConnell in January 2015 — and then the real problems would start.

There's a distinct advantag in being the minority party in the Senate. Despite the frequently mentioned insistence on decorum, Senate Republicans have been consistent in forcing filibuster votes on policy measures and nominations and then maintaining unity in the votes. If and when the Republicans gain power, though, that changes. The insurgencies launched by Texas Sen. Ted Cruz — encouraged by Utah's Mike Lee and other conservatives — will make McConnell's job nearly as difficult as House Speaker John Boehner's has been. In each case, the leaders will face two opposition parties. Boehner was hampered in 2012 and 2013 by his party's unnecessary insistence that House Republicans be able to pass legislation without Democratic votes. If the Senate goes 51-49 for the Republicans, Democrats will filibuster everything in sight, forcing McConnell into the position of necessarily asking Democrats to join him on issues.

New York's Jonathan Chait presented a portrait on Sunday of a world in which Senate Republicans control the majority and inflict their will on the presidency. The threat of the Senate blocking a Supreme Court nomination until January 20, 2017 is far-fetched and unprecedented. But, Chait notes, it's only hard to imagine because "because things that haven’t happened before are hard to imagine." This will all take place within the context of Republican Senators like Cruz and Kentucky's Rand Paul running for president, competing for conservative votes in the Republican primary. It could be very painful for President Obama.

But on a day-to-day basis, it's far more likely to be painful for Mitch McConnell. For the past few years his job has been simply to encourage 41 of his members to vote no on proposals that the party opposes. Next January, he would be forced to call up Democratic senators like West Virginia's Joe Manchin to ask for his help in passing legislation — and to do everything in his power to keep Ted Cruz and Mike Lee from going sideways.

John Boehner learned a valuable lesson about working with Tea Party conservatives during last year's shutdown. By purging them from this year's primaries, Mitch McConnell may simply be setting himself up to learn the same lesson in 2015.