“If you nominate the wrong candidate, as we have been prone to do sometimes, it diminishes your chances in the general election,” said Sen. Saxby Chambliss (R-Ga.), whose announced retirement triggered a crowded May 20 primary race for his seat. (He is staying neutral in the fight.) “It makes it more of an uphill battle if you have a candidate who is not appealing across the board.”

This year, the national party has shifted tactics. The GOP’s Senate campaign committee has aggressively courted critics on the right while other establishment-aligned groups have sought to prop up their preferred candidates. Republican officials have trained candidates of all stripes, even putting them through “campaign schools” to gird them for the stresses of the trail. And national party officials have stood up to outside groups targeting sitting GOP senators, at times suggesting they’re more interested in raising money from activists than helping the broader party’s cause…

Texas Sen. John Cornyn, who ran the NRSC in 2010 and 2012, said the past two elections “have been a learning experience for all of us.” The tea party, he said, was the “wind at our backs in 2010,” helping the party pick up seven seats that year, even though it left several potential wins on the table.

“Then we got divisions within the Republican Party that produced candidates who could get nominated but who couldn’t get elected in the general election,” Cornyn said. “And that’s obviously not the goal.”