Former U.S. Ambassador to Japan Bill Hagerty rode the endorsement from President Trump to victory Thursday in a hotly contested Republican Senate primary in Tennessee.

The Nashville businessman emerged from a tough challenge from trauma surgeon Manny Sethi, backed by Sens. Ted Cruz of Texas and Rand Paul of Kentucky, to clinch his party’s nomination for the seat of retiring Republican Sen. Lamar Alexander.

Hagerty will face Marquita Bradshaw who won the Democratic primary on the same evening, with her result declared less than an hour later.

Republicans are heavily favored to keep the seat, considering the GOP has held both Tennessee Senate seats since 1994.

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Former U.S. Ambassador to Japan Bill Hagerty, right, emerged from a tough challenge from trauma surgeon Manny Sethi, left, to victory Thursday in a contested Republican primary for an open U.S. Senate seat in Tennessee. (Facebook)

Last July, Trump let Tennessee voters know he would back Hagerty for the seat, months before he declared himself a candidate. Sethi had already been running for about a month when Trump’s tweet turned the contest upside down.

Hagerty proceeded to ignore Sethi for most of the campaign, until back-and-forth attacks opened up a few weeks ago and never slowed down. Hagerty leveraged Trump’s endorsement to brush back attacks on his previous business and political ties to Mitt Romney, who was once the GOP presidential nominee and now, according to Hagerty, is a “weak-kneed” Republican senator who voted to convict Trump during the impeachment trial.

Hagerty spent more than $9.6 million on the race through mid-July, compared to the $4.2 million spent by Sethi. Several million more dollars combined have been spent by outside groups on both sides.

Hagerty was backed by big political names with campaign cash, including Sen. Alexander through his PAC and former Gov. Bill Haslam, for whom Hagerty served as state economic development commissioner.

The coronavirus pandemic took in-person campaign events off the table for a couple of months, and the continued outbreak kept Trump from showing up for what initially seemed like a guaranteed visit on Hagerty’s behalf.

The president and several others from his inner circle instead opted to join Hagerty and supporters for tele-town halls. Trump headlined two of them, including on Wednesday night, hours before Election Day polls opened.

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The race also came and went without a debate between the two main candidates. Few policy disagreements rose between them. Additionally, both opposed requiring masks in public to combat COVID-19, and their campaign events often featured few attendees in masks. The candidates themselves were often unmasked when posing for photos with supporters.

Fox News' Paul Steinhauser and The Associated Press contributed to this report.