JACKSONVILLE, Fla.—For months after Republican Adam Putnam entered the Florida gubernatorial race, he seemed almost unbeatable. He had a record of government experience and political success, a trove of endorsements, robust fundraising and a solid lead in most polls over his principal rival, GOP Rep. Ron DeSantis.
Then Mr. DeSantis, a vocal defender of President Trump, picked up the president’s endorsement in June, touted it in a new ad, and appeared with Mr. Trump at a campaign rally in Tampa. Mr. DeSantis shot to the lead in the polls.
“The fallout from the president’s visit to Florida was one of the most incredible things I’ve ever seen,” said Mr. Putnam, the state agriculture commissioner, who has worked ever since to catch up in advance of Florida’s Aug. 28 primary election.
After more than two decades of tension within the GOP between a restive base and its traditional establishment, Trumpism, the archetypal grass-roots movement, is winning.
With the 2018 primaries about to end, all but two of the 37 Republicans Mr. Trump has endorsed for House, Senate and governor during their primary campaigns have won. Mr. Trump has abandoned or undercut the party’s traditional commitment to free trade, fiscal conservatism and a hawkish foreign policy.
Mr. Trump’s most vocal GOP critics in elective office—none more forceful than Sen. John McCain of Arizona, who died Saturday—have been defeated in primaries, announced their retirement or gone quiet.
House Speaker Paul Ryan of Wisconsin, once a rising star of the party and free-market conservatism, is retiring. Of the 33 House and Senate Republicans quitting Capitol Hill in 2018—not including those running for higher office—just two supported Mr. Trump in 2016 before he became the presumptive nominee. At least five of them didn’t endorse Mr. Trump after he won the nomination.
Mr. Trump, thus far, has retained strong support from Republican voters, giving him leverage to yank the party into his orbit. His involvement in primaries represents a departure from the 2016 campaign, when Mr. Trump often acted more like an independent than a Republican standard-bearer.
“The base wants to know what I want,” Mr. Trump said in an interview. “I’ve always heard all my life that if you endorse somebody, it’s nice to have, but it doesn’t mean anything in terms of points…I’m raising people.”
Mr. Trump sees his role as mobilizing voters. “It energizes my people much more than it energizes [opponents],” he said.
The president’s supporters say the policies and candidates he is advancing bring the party more in line with what GOP voters want.
“ Donald Trump’s views are a reflection of what rank-and-file Republican voters have already believed for many years,” said Andy Surabian, a Republican strategist and former Trump White House official. “Republican voters across the country have been ignored by Republicans in Washington, D.C.”
Some GOP leaders say the president’s endorsements could hurt their chances in the general election by advancing candidates who could alienate swing voters or mobilize Democrats to even more vigorous opposition.
The conviction of Paul Manafort, Mr. Trump’s former campaign chairman, on eight counts of fraud, and a guilty plea from his former lawyer Michael Cohen on criminal charges including campaign-finance violations raise the stakes, both for midterm election candidates aligned with the president and for the president himself, who needs all the congressional allies he can get. For now, Republicans in Congress aren’t breaking from the president, but they are trying to keep their distance from the scandals.
“Today, in August 2018, within the Republican party, Trump is dominant,” said Tim Miller, a GOP strategist who was a spokesman for an anti-Trump super PAC in 2016. “But what he has not really done is build a permanent infrastructure of people who share his world view. He has just an infrastructure of allies.”
For now, former House Speaker John Boehner (R., Ohio) said at a GOP gathering earlier this year, “the Republican party is kind of taking a nap somewhere.”
The handful of Republicans willing to challenge Mr. Trump on issues such as immigration may not be back in Congress next year. Of the 23 House Republicans who signed a petition to force a vote on centrist immigration legislation this year, only three are in safe seats, according to the nonpartisan Cook Political Report. Fourteen are running in competitive districts. Six are retiring.
Another Trump critic, GOP Sen. Jeff Flake of Arizona, saw his home-state approval ratings drop from 42% in early 2016 to 33% in late 2017, according to Morning Consult, a polling company that tracks senators’ ratings quarterly. In October 2017, he announced he was retiring from the Senate.
In South Carolina, Rep. Mark Sanford was blindsided by a little-known primary challenger who questioned his loyalty to the president. Michigan Lt. Gov. Brian Calley, who disavowed Mr. Trump in 2016 after an “Access Hollywood” video showed him talking about groping women, was the state establishment’s choice for governor in 2018 but lost the primary.
“The anti-Trump movement is gradually being pushed to the side,” said former House Speaker Newt Gingrich, a Trump ally. “He is growing a Trump Republican Party which will turn the never-Trumpers into a fossilized remnant of bitter-enders.”
The rift between the GOP’s internationalist free traders and its more populist, nationalist wing was evident in 1992, with the presidential campaign of Pat Buchanan, who challenged George H.W. Bush in the primary. The insurgent forces gathered steam with the 2009 emergence of the Tea Party.
Every president makes a mark on his political party—sometimes a profound one. Bill Clinton engineered a turn to the center for Democrats in the 1990s; Ronald Reagan opened a new era of conservatism for Republicans in the 1980s.
Most modern presidents, however, have stayed out of primaries. Barack Obama occasionally endorsed incumbents, but was widely criticized for being aloof and indifferent to his party’s fortunes. Mr. Reagan refused to endorse his own daughter, Maureen, in her 1982 bid for Senate in California.
Mr. Trump’s political team has a process in place that requires candidates to fill out questionnaires and be interviewed if they want to be considered for Mr. Trump’s backing, according to a senior Trump adviser.
The president has endorsed some Republicans who criticized him or opposed elements of his agenda, such as Rep. Martha Roby of Alabama or Rep. Dan Donovan of New York. Senate candidates he has endorsed have mostly been in concert with such establishment party leaders as Kentucky’s Sen. Mitch McConnell.
Still, in a spate of gubernatorial endorsements this summer—in Georgia, Michigan, Kansas and Florida—he has been at odds with the party establishment’s favorites and, for the most part, has gotten the best of them.
In Georgia’s GOP gubernatorial runoff, Mr. Trump backed Secretary of State Brian Kemp, a self-described “politically incorrect conservative,” over the lieutenant governor. In Kansas, he backed the firebrand conservative Kris Kobach over the incumbent governor.
Washington Gov. Jay Inslee, chairman of the Democratic Governors Association, said he is delighted. “Almost all their candidates for governor have shackled themselves to the…Titanic, which is the Donald Trump party,” he said. “That makes it easier for us to defeat them.”
Only two candidates have lost a primary so far after being endorsed by Mr. Trump. Sen. Luther Strange of Alabama was defeated in the GOP special election runoff in September 2017. In last week’s Wyoming GOP gubernatorial primary, conservative businessman Foster Friess lost his bid despite an Election Day Trump endorsement.
In the Arizona race for Mr. Flake’s open seat, pro-Trump credentials are being touted by all three Republicans, whom a local columnist called the “MAGA Triplets,” using the acronym for Trump’s campaign slogan, Make America Great Again. Even Rep. Martha McSally, the GOP establishment favorite who kept her distance from Mr. Trump in 2016, is portraying herself as a Trump ally. The president hasn’t endorsed a candidate in the race yet.
The Florida gubernatorial primary poses a high-profile test of strength for the president. His 2016 margin in the state was less than two points, and his July rating was 50% approve, 46% disapprove, according to Morning Consult.
Mr. DeSantis, a Navy veteran and Tea Party favorite, ran for Congress in 2012, when he earned his first admiring tweet from Mr. Trump. In the House, he joined the hard-line conservative Freedom Caucus.
He has since caught the president’s attention as a regular on Fox News, according to a Trump adviser. Mr. DeSantis has been a Fox guest 93 times from July 2017 to August 2018, more than any other elected official, according to an analysis by Media Matters for America, a liberal watchdog group.
One of Mr. DeSantis’s ads features his baby in a “Make America Great Again” onesie and the congressman telling his daughter, playing with blocks, to “build the wall.”
Mr. DeSantis said he was “proud to have the president’s support,” but added that he wasn’t relying on the endorsement alone. “Ultimately, you’ve got to bring it home.”
His opponent, Mr. Putnam, was elected to the Florida state legislature in 1996, at age 22. He was elected in 2000 to the U.S. House, where he served for five terms and became the No. 3 House GOP leader. He returned to Florida after being elected commissioner of agriculture in 2010.
Mr. Putnam had backed former Florida Gov. Jeb Bush for president in 2016 and, after the release of the “Access Hollywood” video, called Mr. Trump’s comments “vile.” Mr. Putnam now says he is as loyal to the president as Mr. DeSantis, but that issues important to Florida should be the main focus of the campaign. He casts his rival as a tool of the White House who is ignorant of Florida and its water, farm and infrastructure needs.
“You can take everything my opponent knows about water and put it on your sticky note—and still have room left over for your grocery list,” he said at their second debate, at Jacksonville University. “You are running on an endorsement.”
Mr. DeSantis responded by calling his rival an “errand boy” for the sugar industry, which backs Mr. Putnam and has been criticized by environmentalists for contributing to water pollution in Florida. Calling his rival’s support for the president “inauthentic,” Mr. DeSantis said, “This is a career politician trying to tell you what you want.”
Mr. Trump’s endorsement was important to Tom Esposito, 20, a Jacksonville University student active in the Florida Federation of College Republicans. “In today’s era, we need someone who can embrace the values of the Republican Party in the way Donald Trump did,” he said.
That sentiment has hurt politicians like former Minnesota Gov. Tim Pawlenty, a Trump critic in the 2016 election who unexpectedly lost his bid for a comeback in his state’s Aug. 14 GOP gubernatorial primary.
“The Republican Party has shifted,” said Mr. Pawlenty, who had been leading in the polls, after his loss. “It is the era of Trump, and I’m just not a Trump-like politician.”