STRATHAM, N.H. — Returning to the same New Hampshire farm where he launched his last presidential campaign, Mitt Romney on Wednesday insisted he would not pursue a third White House bid but called on voters to punish President Barack Obama by giving Republicans the Senate majority this fall.

“I know that the president is not on the ballot this November, but the people of New Hampshire have a chance to vote on what they think about the president’s agenda,” Romney told hundreds of people gathered under a beating sun as he endorsed former Massachusetts Sen. Scott Brown’s New Hampshire Senate campaign.

Romney criticized Brown’s opponent, Democratic Sen. Jeanne Shaheen, as a “Simon Says senator” who blindly follows Obama’s wishes.

The day was supposed to be focused on Brown’s quest to defeat Shaheen this fall, part of a larger Republican push to pick up the six seats needed to claim the Senate majority for the final two years of Obama’s presidency.

But Romney’s return to the state where he began and ended his last presidential campaign loomed over the event.

The rally took place at Scamman’s Bittersweet Farm, the same location where the former Massachusetts governor formally launched his second presidential campaign three years earlier.

Romney was mobbed by supporters – some wore T-shirts from his last campaign – after his brief remarks. Several people encouraged him to launch another presidential campaign. As he has done consistently in recent months, Romney insisted he had no interest. He said the Republican Party would likely have 14 or 15 candidates to pick from.

“I’m going to get behind the one who I think has the best chance of winning,” he said and later added, “We’ll get someone who can win.”

Brown noted Romney’s special relationship with New Hampshire, where the former Massachusetts governor has a summer home.

“New Hampshire knows Mitt Romney very, very well, and not just because he won the presidential primary here,” he said. “We know him as the upright and capable man who we wish were president right now.”

Brown’s advisers see Romney as a unifying force for New Hampshire Republicans still divided about Brown’s candidacy. The former Massachusetts senator formally moved to the state several months ago.