Trump's endorsement decisions have shaped nearly every major Republican primary for years.
This year, as the 2026 midterms heat up across the country, one race has former senators and an Ex-Trump State Department appointee battling it out for a comeback.
And Trump made one move in a key 2026 Senate race that left a candidate who was one of Trump’s own former ambassadors completely stunned.
Trump backs Sununu over his own former ambassador
President Trump officially endorsed former Senator John Sununu in New Hampshire's Republican primary on Sunday, delivering a crushing blow to his rival Scott Brown in one of the most closely watched Senate races of the 2026 cycle.
Trump called Sununu an "America First Patriot" and said he had his "Complete and Total Endorsement."
"John will work tirelessly to Grow our Economy, Cut Taxes and Regulations, Advance MADE IN THE U.S.A., Unleash American Energy DOMINANCE, provide Affordable & High-Quality Health Care, Champion School Choice, Keep our Border SECURE, Stop Migrant Crime, Support our Brave Military, Veterans, and Law Enforcement, Ensure LAW AND ORDER, and Defend our always-under-siege Second Amendment," Trump wrote on Truth Social.
The timing couldn't be worse for Brown, who served as Trump's ambassador to New Zealand and Samoa during the first administration.
Brown has been positioning himself as the more Trump-aligned candidate throughout the primary, while Sununu notably wrote a 2024 op-ed calling Trump a "loser" while endorsing Nikki Haley in the presidential primary.
Yet Trump sided with Sununu anyway, recognizing the former senator gives Republicans their best shot at flipping the seat held by retiring Senator Jeanne Shaheen.
Trump's endorsement just ended Brown's comeback dreams
Sununu already led Brown 48% to 25% in polling from the University of New Hampshire Survey Center before Trump's endorsement.
That gap will only widen now.
Trump's endorsement is the single most valuable asset in Republican primaries, freezing donor money and clearing the field for his chosen candidates.
National Republican Senatorial Committee Chairman Tim Scott moved quickly to endorse Sununu after Trump's announcement, calling it proof that "Republicans are fully prepared to show up in November."
Brown pledged to "keep working" after Trump passed him over, insisting voters "deserve a choice between candidates."
But political insiders know Trump's endorsement just ended the competitive portion of this primary.
Sununu comes from one of New Hampshire's most prominent political families – his father served as White House Chief of Staff under President George H.W. Bush, while his brother Chris served four terms as governor.
That name recognition combined with Trump's backing makes Sununu the prohibitive favorite to win the September 8 Republican primary.
The Senate comeback that history says can't happen
Here's what makes this race fascinating beyond the primary drama.
Sununu is attempting something almost impossible – returning to the Senate after losing reelection nearly two decades ago.
He first won the seat in 2002, defeating Shaheen in her bid to move from the governor's mansion to Washington.
Shaheen got her revenge in 2008, ousting Sununu in a rematch during the financial crisis and Obama wave.
Slade Gorton pulled off the last successful Senate comeback in 1988, and nobody's managed it since.
The historical record is brutal for Senate comeback attempts.
Since 1946, roughly 220 senators lost reelection bids.
Only 17 eventually won their way back to the chamber, and the vast majority did so within one or two election cycles while their political operations remained intact.
Sununu is trying to defy history after being out of office for 18 years.
Brown is attempting his own unlikely comeback after losing his Massachusetts Senate seat to Elizabeth Warren in 2012, then losing to Shaheen in New Hampshire in 2014.
The New Hampshire primary features two former senators trying to overcome historical odds that say comeback attempts almost always fail.
But Trump just made Sununu's odds significantly better while effectively ending Brown's chances before voters even cast ballots.
Republicans believe the open seat gives them one of their best pickup opportunities in a challenging midterm map where they're defending more competitive seats than Democrats.
Early general election polling shows Democrat Congressman Chris Pappas leading Sununu by a narrow 46.3% to 42.7% margin.
That makes New Hampshire one of the most competitive Senate races heading into November 2026.
Sources:
- David Hawkins, "Trump Endorses Former Senator in Closely-Watched New Hampshire Senate Race," Slay News, February 2, 2026.
- Nathan Gonzales, "Trump continues to play kingmaker in Republican primaries," Roll Call, January 20, 2026.
- J. Miles Coleman, "Getting Back to the Senate: Defeated Senators Who've Returned to Office," Sabato's Crystal Ball, September 25, 2025.
- Alexandra Marquez, "Ex-U.S. Sen. John E. Sununu enters GOP primary race in N.H. for the seat he lost in 2008," WBUR News, October 22, 2025.
- John Bowden, "Trump endorses John Sununu in New Hampshire Senate race," NBC News, February 1, 2026.
