Trump's endorsement power faces new test in Louisiana Republican Senate showdown

President Donald Trump's immense clout over the GOP and the power of his endorsements in Republican nomination races faces its latest test Saturday, as Louisiana holds primary runoff elections for the U.S. Senate.

Six weeks after denying Trump-targeted GOP Sen. Bill Cassidy a third six-year term in the Senate, Republican voters in the solidly red Gulf Coast state will choose between Rep. Julia Letlow and state Treasurer John Fleming for the now open seat.

A Letlow victory in the GOP runoff would be another victory for Trump as he works to fill the halls of Congress with loyal lawmakers for his final two years in the White House. But a win by Fleming would be the third high-profile endorsement setback for Trump in this spring's Republican primaries.

Five years after he voted to convict Trump in his second impeachment trial, Cassidy was sent packing.

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Letlow, who was backed by Trump even before she entered the race in January, grabbed 45% of the vote in the primary, with Fleming at roughly 28% and Cassidy at just under 25%. Since no candidate cracked 50% of the vote, Letlow and Fleming advanced to the runoff for the Republican nomination and Cassidy became the first elected Republican senator to lose renomination since Sen. Richard Lugar of Indiana in 2012.

Trump, celebrating Cassidy's defeat, said on social media that "it’s nice to see that his political career is OVER!"

Cassidy, in a speech to supporters after conceding, took a jab at Trump, saying, "When you participate in democracy, sometimes it doesn't turn out the way you want it to. But you don't pout, you don't whine. You don't claim the election was stolen… You don't manufacture some excuse."

Letlow, who is also backed by Louisiana Gov. Jeff Landry, a top Trump ally, won her congressional seat in 2021, after her husband, Luke Letlow, died six days after being sworn into the U.S. House after his 2020 election victory for the seat she now holds. She has highlighted her support from Trump throughout her Senate campaign.

Fleming, who spent eight years in Congress before serving as a White House deputy chief of staff during Trump’s first term, has argued that he's the most conservative candidate in the GOP Senate primary.

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The GOP nominee will be considered the clear frontrunner in the midterm election against either farmer Jamie Davis or Navy veteran Gary Crockett, who are facing off in the Democratic Senate runoff.

The brute force of the president's endorsement power has been on display in GOP primaries over the past two months, with his candidates ousting incumbents he targeted in showdowns in Indiana, Kentucky and Texas, as well as the Louisiana primary.

But Trump's endorsement streak in statewide and congressional Republican primaries was snapped a few weeks ago when his last-minute endorsement of Republican Rep. Randy Feenstra of Iowa in the race to succeed retiring GOP Gov. Kim Reynolds wasn't enough to propel the three-term congressman to victory.

Feenstra was narrowly edged by Zach Lahn, a businessman, farmer and former political strategist who was backed by the political wings of MAHA — the acronym for the Make America Healthy Again movement aligned with Trump's Health Secretary Robert F. Kennedy Jr. — and Turning Point USA, the powerful conservative organization co-founded by the late Charlie Kirk.

The president rebounded three weeks ago in South Carolina, as Trump-backed Lt. Gov. Pam Evette finished first in the GOP gubernatorial primary and longtime Trump ally Sen. Lindsey Graham won a majority of the vote in the Republican Senate primary, and avoided a runoff.

Graham, who was endorsed by Trump, was facing primary challenges from five candidates, including conservative businessman Mark Lynch, who took aim at the senator over his support for the war in Iran. Lynch was backed by some MAGA leaders who have been critical of the president.

Two weeks ago, Trump-backed candidates won two of the three top races in Georgia and Alabama, with the one setback coming against a billionaire businessman who shelled out over $100 million of his own money to boost his campaign.

Rep. Barry Moore, a House Freedom Caucus member and longtime Trump supporter who was endorsed by the president, comfortably defeated rival Jared Hudson, a former Navy SEAL sniper who was supported by some top names on the right, in solidly red Alabama's GOP Senate runoff.

In battleground Georgia's Republican Senate runoff, an 11th-hour endorsement by Trump helped boost Rep. Mike Collins, a MAGA champion, to victory over former college football coach Derek Dooley, who was backed by popular conservative Gov. Brian Kemp.

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Collins will face Democratic Sen. Jon Ossoff in the general election in a race that's among a handful that will likely decide if the GOP holds its slim majority in the chamber in the midterms.

But in Georgia's GOP gubernatorial runoff, the candidate Trump backed, Lt. Gov. Burt Jones, who was also endorsed by Kemp this past weekend, was defeated by billionaire businessman Rick Jackson, who ran as an outsider.

On Tuesday, Trump-backed first-time candidate Anthony Constantino, a businessman and former boxer, defeated Robert Smullen, a retired Marine Corps colonel and New York assemblyman who had the backing of the state party, in the upstate New York race to succeed retiring GOP Rep. Elise Stefanik.

Meanwhile, in South Carolina's Republican gubernatorial runoff, Trump couldn't lose.

That's because, besides backing Evette, he also gave a last-minute endorsement to state Attorney General Alan Wilson, who ended up winning the showdown in a landslide.