In Nevada, veteran Sam Brown is launching a campaign to challenge Senator Rosen, entering the GOP field with the backing of the National Republican Senatorial Committee.

In 2022, Mr. Brown came in second in the Nevada GOP Senate primary, after Attorney General Adam Laxalt, receiving 34.2 percent of the vote to Mr. Laxalt’s 55.9 percent. Mr. Laxalt went on to narrowly lose to Senator Masto in the general election.

As in 2022, Nevada is expected to be a swing state in 2024 as Democrats defend their Senate majority. After West Virginia, Montana, and Ohio, Nevada will be one of the most competitive states in next year’s Senate elections.

Now, Mr. Brown is launching another campaign for the Senate with the backing of the NRSC, which is closely aligned with the minority leader, Senator McConnell.

“Right now, the American Dream is at risk. Joe Biden and Jacky Rosen promised to unite Americans and solve problems. Instead, they’ve abandoned Nevada and divided America with extreme policies to satisfy special interests in Washington,” Mr. Brown said in a statement, referring to Nevada’s senior senator.

Since the 2022 election, Mr. Laxalt has been hired as the chairman of the Never Back Down PAC, which is supporting Governor DeSantis’s bid for the presidency.

Mr. Brown is likely entering the race as an early favorite based on his past, given his favorable performance in last year’s GOP primary, though there haven’t been GOP Senate primary polls as of yet.

Also running is a state assemblyman, Jim Marchant, who lost a bid for secretary of state of Nevada to Francisco “Cisco” Aguilar by three points last year, and a failed California House candidate, Ronda Kennedy, who received 8.5 percent of the vote in the primary for California’s 30th House District last year.

Mr. Marchant was endorsed by President Trump in his run last year, in part due to his refusal to acknowledge the results of the 2020 election. It’s not yet clear whether Mr. Trump will be supporting him in his Senate bid.

Mr. Brown is currently the only candidate in the race who enjoys any support from the national GOP, with the NRSC putting out a statement in support of his candidacy Monday.

“Sam Brown’s life of service and sacrifice is an inspiration to all Americans,” the NRSC chairman, Senator Daines, said. “I am very pleased that Sam is stepping up to run for the U.S. Senate.”

In the analysis of an associate editor at Sabato’s Crystal Ball at the University of Virginia Center for Politics, Miles Coleman, the open question in the race is whether both Mr. Trump and the NRSC will support the same candidate.

After the 2022 election cycle, during which Mr. Trump was at odds with the NRSC and other Republican committees throughout the nomination process, Mr. Daines offered Mr. Trump and his followers an olive branch by endorsing Mr. Trump for president in April.

“Will Daines’s support make Trump more likely to support the NRSC’s preferred candidates?” Mr. Coleman asks the Sun. “This race may be a good test of that. We know how much Trump values loyalty, so you’d almost expect him to back Marchant. So a Brown endorsement would catch my attention.”

Zooming out, most handicappers give Democrats a slight advantage in Nevada, with both the Crystal Ball and the Cook Political Report rating the state as leaning Democratic on the Senate level.

Mr. Coleman attributes this, in part, to the fact that there aren’t any “top tier candidates lining up to challenge Rosen,” adding that “Brown or Marchant could get the job done if the environment turns enough against Democrats.”