House Speaker Paul D. Ryan flatly ruled out becoming the Republican presidential nominee this year, insisting Tuesday that he would refuse all entreaties to accept the role — though he would try to shape the agenda that the party carries into November.
His announcement denies the party its brightest rising star and leaves the Republican establishment still searching for an alternative to the current presidential field.
Even there, Mr. Ryan seemed to foil establishment hopes by saying he wants the Republican National Convention — where he will serve as chairman — to adopt a rule that requires the nominee to be someone who has filed as a candidate for the White House. That would rule out not only himself but also 2012 nominee Mitt Romney.
“I really believe if you want to be president, you should run for president,” Mr. Ryan said at a brief press conference at the national Republican Party headquarters.
He said he felt compelled to once again reject attempts to recruit him after facing questions about his political future during a trip to the Middle East over the weekend.
Those questions are unlikely to fade, even with his flat refusal.
Indeed, Mr. Ryan gave similar signals last year when fellow Republicans tried to recruit him to be House speaker after the resignation of John A. Boehner, Ohio Republican. In the end, Mr. Ryan relented under pressure and easily won the top job in Congress.
On Tuesday, the Wisconsin Republican insisted the White House is a “completely non-sequitur comparison.”
“Being speaker of the House is a far cry from being president of the United States because I was already in the House,” he said. “I will not allow my name — I am opposed to my name being put in.”
Republican political strategist Jim McLaughlin said Mr. Ryan helped all the presidential candidates by removing himself from a convention fight for the nomination.
“It helps whoever is left in the game,” he said. “Paul is basically saying it can’t be someone who isn’t running for president.”
Mr. McLaughlin said Mr. Ryan’s presence in the race, even if only as a subject of speculation, would make it harder for either Donald Trump or Ted Cruz to firm up support among delegates.
“Look at the negatives that Trump and Cruz are accumulating, not just with general election voters but also with primary voters. I think that when you have someone like Paul Ryan taking his name out, he’s basically saying it can’t be someone who isn’t running for president,” he said. “So I think it helps whoever is left in the game.”
Mr. Ryan said he still expects to play a role in shaping the party’s agenda. He and fellow House Republicans have been working on a policy document that he said they will introduce “in the next few months.”
It’s unclear how that will jibe with the nominee’s ideas.
Mr. Ryan became speaker late last year and has made a concerted push to lead the party’s efforts to sell itself to voters.
But he has struggled with some of the tasks on Capitol Hill, including the annual budget. Republicans will miss the Friday deadline, set in law, for approving a fiscal blueprint — a particular black eye for Mr. Ryan, a former chairman of the Budget Committee.
“The American people aren’t worried about Speaker Ryan’s plans for his political future. What they are worried about is a dysfunctional Republican Congress more interested in stacking the deck for the special interests than doing the basic business of governing,” the office of House Minority Leader Nancy Pelosi, California Democrat and a former speaker, said in response to Mr. Ryan’s press conference.