In Republican electoral politics, there are few surer ways to guarantee a primary fight than to challenge party orthodoxy on guns. Running afoul of gun voters is cited as a reason veteran Senator Dick Lugar did not survive his last primary in Indiana. Eric Cantor was House Majority Leader when a tea party challenger preferred by Second Amendment hardliners snuck up on him in 2014.

But when Pennsylvania Republicans go to the polls next week, they will see just one name on the ballot for the Senate: Pat Toomey, co-author of legislation that attempted to introduce the most expansive new gun restrictions in two decades. In the wake of the Sandy Hook school shooting, Toomey co-sponsored a 2013 law backed primarily by Democrats and President Barack Obama that would have narrowed the so-called gun show loophole.

That no one mustered a candidate to challenge Toomey can likely be attributed to Pennsylvania demographics, local political experts say. The more populous (and thus vote-rich) eastern end of the state is heavily suburban, and Republicans there are less invested in doctrinaire gun politics. “Most Pennsylvania conservatives won’t hold it against him,” says Robert Speel, a professor of political science at Penn State-Behrend. A March poll by Franklin & Marshall College found that 59 percent of Pennsylvanians support new gun laws, compared to 38 percent who oppose them.

Other data indicates that Toomey is also one of the most vulnerable incumbent Senators up for reelection this year. Speel believes that the state’s conservatives recognize that he has a better chance of holding the seat than a more ideologically pure alternative. Gun-rights groups may be making the same calculus.

“I wouldn’t say it’s easy for state officials to cross the [National Rifle Association],” since they can carry a lot of weight in small local elections, says Speel. But when it comes to national office, “the NRA and gun-rights groups realize that if there’s an even more conservative nominee than Toomey, they would be likely to lose the general,” he says.

Lacking a challenge from the right, Toomey has embraced his gun record, touting it on the campaign trail.

Toomey’s campaign has run television ads specifically highlighting his gun reform efforts and ties to gun violence prevention advocates. Had it passed, the 2013 legislation that Toomey pushed alongside West Virginia Democrat Joe Manchin would have become the strongest new gun law since the background check system was created under President Bill Clinton in 1993. All commercial gun sales, including those conducted by amateur gun dealers at gun shows or arranged over the internet, would have been subject to background check requirements. Under current law, in most states only federally licensed gun dealers must perform such checks. (The Manchin-Toomey bill failed in the Senate in April 2013, after it did not secure enough votes to ensure a filibuster-proof majority.)

“Our campaign is going to promote all aspects of Pat Toomey’s record and leadership,” says Mark Harris, a Republican strategist working to reelect Toomey. “The Manchin-Toomey background checks legislation is an important part of his record and we are proud to promote it.”

The NRA has been critical of Toomey and his defeated bill: The group called it “misguided” and has referred to the senator as a “gun control supporter” — a label that in other races could be a kiss of death. But the gun group has stopped short of an all-out attack.

Though some political scientists believe Republicans’ staunch opposition to new gun laws has become a kind of “litmus test” for conservatism, Toomey’s campaign is gambling that Pennsylvania Republican voters — at least — either agree with his stance or will decide that they can vote for him despite it.

Toomey received an A grade from the NRA when he first ran for Senate in 2010. The gun group issues new ratings in advance of each election, and has posted the for some Pennsylvania Republicans running for the House of Representatives in the 2016 primary cycle — but it has not yet publicly updated Toomey’s score. If he is due a downgrade, his campaign says it is unbothered by that prospect.

[Photo: AP/Marc Levy]