U.S. Senator Lindsey Graham (R-SC) (Photo by Alex Wong/Getty Images) U.S. Sen. Lindsey Graham (R-S.C.) (Alex Wong/Getty Images)

Mainstream GOP senators should stop looking over their right shoulder. It’s harder than one might think to primary them from the right. When you look at those most at risk from a right-wing challenge, you see they don’t have all that much competition. In Wyoming, Liz Cheney is off to a rocky start against Sen. Mike Enzi. The last poll had Enzi ahead by more than 50 points. In Kentucky, Sen. Mitch McConnell’s tea party gadfly opponent Matt Bevin peppers the national media with releases and e-mails. However, not even the Club for Growth, one of the primary search-and-destroy-fellow-conservatives groups, is backing him. Public polling is scant, but Bevin was 40  points back in August. There is one group that is all-in for Bevin: the Democratic Senatorial Campaign Committee. He’s also been hobbled by gaffes and has struggled to explain some tax delinquencies. McConnell has the backing of fellow Republican senators Rand Paul (Ky.) and Marco Rubio (Fla.) and has raised a boatload of cash. (McConnell’s real challenge will come in the general election against Kentucky Secretary of State Alison Grimes.) In Texas, Sen. John Cornyn doesn’t have a serious competitor. The deadline to file is Dec. 9. (Maybe the junior senator from his state will now endorse him.) Even Sen. Lindsey Graham (R-S.C.), who right-wing media insists is “vulnerable,” has yet to break a sweat. A conservative blog reports, “In the state’s regularly scheduled Senate election for 2014, Sen. Lindsey Graham, R, holds a commanding lead in the primary, with 51 percent of the vote, just above the threshold he’d need to avoid a runoff against the second-place finisher. Graham’s closest competition is state Sen. Lee Bright, who pulls in 15 percent. Tied at 4 percent a piece are businessman Richard Cash, 2010 lieutenant governor also-ran Bill Connor, and businesswoman Nancy Mace, the first female to graduate from The Citadel.” His approval with all voters has slid, but among Republicans he is rated favorably by a margin of 55 to 34 percent. This is not to say that it’s impossible for one or more of the incumbents to run into trouble, but it does suggest that unlike Sen. Mike Lee (R-Utah), who took down an incumbent in a closed convention, or Richard Mourdock, the Indiana state treasurer who knocked out Sen. Richard Lugar in the primary before going down in flames in the general election, none of the challengers is well-positioned at this point to bump off an incumbent. Several things may be working against them. Those who saw the challenge coming (McConnell and Graham) were well-prepared, and the remainder (Enzi, Cornyn) have solid conservative records that are hard to impugn. Moreover, after the shutdown crashed and burned, the hard right has lost some of its oomph, and was forced on defense when blamed in part for the defeat of Virginia gubernatorial contender Ken Cuccinelli II (R). After taking flak from colleagues, Lee and Sen. Ted Cruz (R-Tex.) said they wouldn’t be helping the Senate Conservatives Fund to primary fellow GOP senators. In short, there has to be a real reason to boot an incumbent (not simply “doesn’t fight hard enough”), a favorable political climate, an unprepared or out-of-touch incumbent (Lugar was accused of having rarely visited his home state) and at least (maybe at most) one very plausible contender. If any of these is missing, chances are the incumbent will survive. That should tell Republican Senate incumbents to stop worrying about a stray vote here or there or about the ravings of third-party groups and talk radio hosts. If they are ideologically in tune with their state, maintain a good connection with voters and don’t take reelection for granted, it will be very hard to primary them. And that should also tell donors to third-party hit squads like the Senate Conservatives Fund: You are wasting your money going after mainstream, well-regarded incumbents. Maybe, you know, they should try knocking off Democratic incumbents for a change. UPDATE: Cheney supporters remind me that the poll mentioned above was a private one, commissioned by Enzi. (The same polling outfit was off by a country mile in the 2012 Senate primary in Texas, eventually won by Ted Cruz.) The Cheney camp would concede she is behind, but by nowhere near 50 points. When actual public polling emerges, we will have a better sense of how much ground Cheney will need to make up.