News Analysis

CLEVELAND >> Donald Trump and the army of voters he brought into politics, overpowering all attempts at dissent, have pushed through fundamental changes in the Republican Party, many of which seem likely to endure whether or not he wins the White House in November.

After four raucous days and the defiant speech Trump gave in claiming the party’s nomination — as well as the score-settling diatribe he delivered Friday morning — it is hard to imagine the Republican Party returning anytime soon to being the party of free trade, democracy-building around the globe and at least modest immigration reform.

And it is almost as hard to imagine establishment Republicans, waiting in the wings in hopes that Trump’s candidacy was a fever waiting to break, finding a welcome among the delegates who made this their party here in Cleveland, with cheers for Trump and other speakers who positioned themselves as opponents to the party’s status quo.

Whatever still exists of the moderate Republican wing — people like Jeb Bush, the former Florida governor; Mitt Romney, the party’s 2012 nominee; and Gov. John Kasich of Ohio — had virtually no presence at the convention this week. Their absence suggests that the convention was something of a breaking point: There may be no easy return to the Republican Party of the 1990s.

Roger Stone, a longtime adviser to Trump, said this nominee would put his mark on the party, much the same way other powerful presidential nominees have done. “Every successful Republican president — Lincoln, McKinley, Eisenhower, Nixon, Reagan — has remade the party in his own image,” he said. “We are going to be a middle class of working people again. We are leaving the Bush country-club party.”

Trump certainly has much to work with as he assumes control. The convention left little doubt over the depth of opposition to trade pacts, once a central tenet of Republican philosophy, or to easing the path for immigrants who want to become citizens, policies that President George W. Bush, a Republican, championed when he was in office. One by one, Trump, a businessman, has rejected core principles embraced by every Republican president since Richard M. Nixon.

“Trade and immigration are problems for America,” said Trent Lott, a former Republican senator from Mississippi, who supported free trade and immigration reform. “Frankly, we’ve been irresponsible in not dealing with it before now.”

Lott, who skipped the Republican convention, preferring to spend the week traveling in Spain, said Trump had forced the party to make changes that were needed for it to remain viable.

“Trump has got everybody’s attention,” he said.

Trump’s ascension is a turning point in a political evolution that first upended the Republican Party in 2010, when Tea Party insurgents began defeating establishment politicians. The longtime intraparty alliance between disaffected blue-collar whites and the wealthy is unraveling; Trump seized on that change and personified it.

“He’s a product of the new Republican Party,” said Julian E. Zelizer, a Princeton historian. “You’ve had the rise of Tea Party conservatism, which is much more ruthless in how they view their opponents in the Republican Party and how they view Democrats. They were ready for him.”

Scott Brown, the former Republican senator from Massachusetts who won as a Tea Party candidate in 2010, said Trump had “tapped into an anger that’s very similar to what was out there when I ran. It feels like that, but on steroids.”

The critical question now is whether the Republican Party has become the party of Trump only for the course of the campaign — meaning it the party will revert to ideological form if he loses in November — or whether this amounts to a long-term demographic and ideological realignment of one of the nation’s two major political institutions.

Stuart Stevens, a Republican who ran Romney’s campaign for president and is a vociferous critic of Trump’s, said he had little doubt that Trump would lose this fall — but that, after this convention, he was unsure about what would happen to his party.

“If there is a future for the Republican Party, it will be led by those who actively opposed Donald Trump,” Stevens said. “There will be Trump Republicans and non-Trump Republicans.” He said the opponents of Trump today “are the people who are going to have the moral standing to start and try to rebuild the party.”

What is more, Trump faces resistance to his agenda in Congress. Speaker Paul D. Ryan, who was chairman of the convention, and Mitch McConnell, the Senate majority leader, have made no secret of their differences with Trump on foreign policy and economic issues. Both offered him lukewarm endorsements at the convention; McConnell was greeted with a scattering of boos.

Even on the floor of the convention hall, some establishment Republicans questioned the depth of Republican support for the Trump agenda. Bill McCollum, a former congressman and state attorney general from Florida, said Republicans had closed ranks behind Trump, but added: “I don’t know if the party’s really that way now.”

Gary Bauer, a longtime Christian conservative activist and former presidential candidate, said Trump could not expect to transform the party overnight. “It will be an ongoing conversation with him and the party,” Bauer said. “On trade, on reorienting our economic agenda from Wall Street to Main Street, and getting serious about securing our borders.”

Still, in the year since Trump came down the escalator in his New York headquarters to declare his candidacy, his influence on the Republican Party has been far-reaching. Conservatives say he has created a model for Republicans aspiring to national office.

Kris W. Kobach, the Kansas secretary of state, said Trump had changed the party’s orientation on immigration. “His use of that issue as the flagship of his campaign is something that has shifted the center of the party on that issue,” Kobach said. “He has shown that you can base a candidacy principally on that issue and win. It will affect people running for Congress, affect people running for governor.”

Chris Chocola, a former Indiana congressman who sits on the board of the Club for Growth, a conservative advocacy group that opposed Trump, said he could see “all kinds of candidates changing their tune on trade issues.”

“So, at least from a campaign standpoint, the tone has changed,” he said.

Douglas Holtz-Eakin, a top economic adviser to George W. Bush and John McCain, described 2016 as a moment of “creative destruction” for the party, and one that should force it to reconsider its economic agenda. “Objectively, the economic message didn’t sell in 2008,” he said. “It didn’t sell in 2012. And it didn’t change.”

Zelizer, the historian, said Trump’s takeover of the party was “going to have a real lasting impact.”

“The Republicans for many decades have tried to hold together this uneasy coalition. It’s falling apart,” he said. “He’s coming in at exactly the right moment to exploit this.”

© 2016 The New York Times Company