He may not direct a high-powered political-action committee or hold a formal position, but with the two living former Republican presidents — George H.W. Bush and George W. Bush — shying away from campaign politics, Romney, 67, has begun to embrace the role of party elder, believing he can shape the national debate and help guide his fractured party to a governing majority.

Insisting he won’t seek the presidency again, the former GOP nominee has endorsed at least 16 candidates this cycle, many of them establishment favorites who backed his campaigns. One Romney friend said he wants to be the “anti-Jim DeMint,” a reference to the former South Carolina senator and current Heritage Foundation chairman who has been a conservative kingmaker in Republican primaries. Romney’s approach is to reward allies, boost rising stars and avoid conflict.

Romney has signed his name to sharply partisan e-mail appeals and headlined recent fundraisers from Las Vegas to Miami to Boston. This week, he appeared in his first television ad: a U.S. Chamber of Commerce spot supporting Rep. Mike Simpson of Idaho, who faces a tea party challenger in a state where Romney remains widely popular. And Romney’s confidants said he will appear in more ads, record robo-calls and stump at rallies later this year.