If former President Donald Trump’s continued clout over the Republican Party was on the line in Ohio’s highly contested and contentious GOP Senate primary, the former president easily passed the test.

JD Vance, the candidate Trump endorsed less than three weeks ago in the crowded and expensive showdown that has grabbed national attention for months, on Tuesday won the GOP nomination in the race to succeed retiring Republican Sen. Rob Portman.

And the former president, who 15 months removed from the White House remains the most popular and influential politician in the GOP, didn’t waste any time taking credit.

VANCE WINS GOP SENATE SHOWDOWN IN OHIO

"JD Vance put in tremendous work and has immense political talent—which put him in the position to earn the support of President Trump—but it was the endorsement of President Donald J. Trump that took a candidate who many insiders said was in 4th and at single digits in the polls, and in only two weeks, propelled him into a commanding first place finish," Trump spokesman Taylor Budowich told Fox News in a statement soon after Vance’s victory.

Donald Trump JD Vance

Senate candidate J.D. Vance greets former President Donald Trump at a rally at the Delaware County Fairgrounds, April 23, 2022, in Delaware, Ohio. (AP Photo/Joe Maiorana, File)

Trump continues to play a kingmaker’s role in the 2022 Republican primaries as he repeatedly flirts with making another White House run in 2024. And Budowich emphasized that "the power of President Trump’s endorsement is undeniable, his dominance over the Republican powerbrokers in D.C. cannot be overstated, and the promise of this MAGA Movement will not just define the Midterms, but it will win for years to come."

VANCE URGES PARTY UNITY AFTER CONTENTIOUS REPUBLICAN PRIMARY BATTLE

Vance pointed to the former president’s endorsement in his victory speech, saying, "I have absolutely got to thank the 45th President of the United States."

Vance campaign senior adviser Andy Surabian told Fox News his candidate "put in tremendous work and has immense political talent—which put him in the position to earn the support of President Trump—but it was the endorsement of President Donald J. Trump that….propelled him into a commanding first place finish."

JD Vance primary victory in Ohio

Republican Senate nominee JD Vance speaks to supporters after winning a contentious and expensive primary, in Cincinnati, Ohio, on May 3, 2022. (Tyler Olson/Fox News)

Asked if Trump’s backing was the reason Vance came out on top, longtime Ohio based Republican consultant Mike Hartley said "100%."

"Vance was stuck before the endorsement and surged the last two weeks," Hartley, a veteran of numerous presidential and statewide campaigns who remained neutral in the 2022 primary, emphasized.

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Trump, who remains a fundraising giant as he continuously re-litigates his 2020 presidential election loss, has made dozens and dozens of endorsements this cycle all the way up and down the ballot and has crisscrossed the country the past couple of months, holding rallies for some of the top candidates he’s backing.

Vance was Trump’s first test in May, but far from his last. Tuesday’s primaries in Ohio and the neighboring Midwestern state of Indiana kicked off a frenetic schedule this month, with a total of 13 states holding primaries. And Trump-backed candidates face stiffer tests ahead.

Next Tuesday in Nebraska’s combustible three-way fistfight for the GOP gubernatorial nomination, Trump is backing Charles Herbster, a multimillionaire agricultural executive, in the race to succeed term-limited Republican Gov. Pete Ricketts. The contentious race also includes multimillionaire hog farmer Jim Pillen, who is backed by Ricketts, and state Sen. Brett Lindstrom.

Herbster, who in recent weeks has faced accusations that he sexually assaulted eight women, is a longtime top donor and ally of Trump. The former president endorsed Herbster last autumn and held a rally with the candidate in Nebraska on Sunday.

MAY MADNESS: PRIMARY SEASON IGNITES IN EARNEST 

West Virginia holds primaries on the same day as Nebraska, and Trump’s prestige is on the line in an intra-party battle between GOP Reps. David McKinley and Alex Mooney. The state lost a congressional seat during the once-in-a-decade congressional reapportionment, and both Republican incumbents were drawn into the same district. Trump’s backing Mooney in a race that’s partially turned into a test of the former president’s clout.

A week later, on Tuesday, May 17, Trump faces three more stiff tests.

Mehmet Oz

Mehmet Oz, celebrity physician and U.S. Republican Senate candidate for Pennsylvania, speaks during the Conservative Political Action Conference in Orlando, Florida, Feb. 27, 2022. (Tristan Wheelock/Bloomberg via Getty Images)

The former president recently endorsed Mehmet Oz in Pennsylvania’s jam-packed, expensive, and very high-profile GOP Senate primary, in a move that split Trump’s political world and millions of supporters across the country. Trump’s backing of the celebrity doctor known as Dr. Oz did little to temper suspicions among many in the Republican Party about the candidate’s conservative credentials. Polling suggests Oz is locked in a fierce battle with David McCormick, a former hedge fund executive, West Point graduate, Gulf War combat veteran, and Treasury Department official in former President George W. Bush's administration. Three other major GOP candidates are also on the primary ballot.

FOLLOWING TRUMP ENDORSEMENT, OZ AND MCCORMICK TRADE FIRE

In Idaho, Trump is backing far-right Lt. Gov. Janice McGeachin, who is one of seven primary challengers running against incumbent Republican Gov. Brad Little, whom polling suggests is the clear front-runner.

Trump has his best shot of victory on May 17 in North Carolina, where last summer he endorsed Rep. Ted Budd in the state’s open GOP held Senate seat race. For months, Budd was unable to leverage the former president’s endorsement to boost his poll numbers and fundraising figures. But in recent weeks, Budd has surged to front-runner status in the increasingly contentious primary showdown that also includes former Gov. Pat McCrory, and former Rep. Mark Walker.

But a week later, the former president could suffer a major setback in his nearly year and a half long bid to oust Republican Gov. Brian Kemp of Georgia.

Four years ago, with the support of Trump, Kemp narrowly defeated Democrat Stacey Abrams to win the governorship. But Kemp earned Trump’s ire starting in late 2020, after the governor certified President Biden's narrow victory in Georgia in the presidential election following multiple recounts of the vote. Trump, who had unsuccessfully urged the governor and other top Republican officials in the state to overturn the results, has now returned to Georgia twice to campaign against Kemp. 

Trump and Perdue at Georgia rally

Donald Trump shakes hands with former Sen. David Perdue, who's primary challenging GOP Gov. Brian Kemp, at the former president's rally in Cumming, Georgia, on March 26, 2022. (David Perdue campaign)

Trump for months urged former Republican Sen. David Perdue to challenge the governor, and late last year he endorsed Perdue a day after the former senator launched his bid. Perdue declared his candidacy a few days after Abrams, a voting rights champion and rising star in the Democratic Party, launched her second straight bid for governor.

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But regardless of Trump’s endorsement, with three weeks to go until Georgia’s primary, Kemp enjoys large leads over Perdue in two key campaign metrics – public opinion polling and fundraising.