NASHVILLE (AP) — Trauma surgeon Manny Sethi said Monday that he's running for a U.S. Senate seat opening in Tennessee.

Sethi's announcement comes months after Republican Sen. Lamar Alexander said he's not seeking reelection in 2020. In a video, the 41-year-old Sethi described himself as a conservative outsider who supports President Donald Trump.

Republican Gov. Bill Haslam is also mulling a run to replace Alexander but has not yet announced. Haslam had said he would make a formal decision within months of leaving office in January.

While Haslam is the most prominent Republican considering a run, GOP U.S. Rep. Mark Green has also said he's weighing a bid for Alexander's seat. Club for Growth, a conservative group urging Green to run, has already begun waging preemptive attacks against Haslam.

U.S. Ambassador to Japan Bill Hagerty has also been mentioned as a possible Republican Senate candidate.

Sethi's campaign team will feature Chris Devaney, who took on the role of special assistant to Republican Gov. Bill Lee after running the first-term governor's 2018 race as campaign manager. Devaney was finishing his last day with the Lee administration on Monday, said Lee spokeswoman Laine Arnold.

On the Democratic side, Nashville attorney and former Army helicopter pilot James Mackler has also entered the Senate race. Mackler dropped out of the 2018 contest to replace Republican former U.S. Sen. Bob Corker, stepping aside when former Democratic Gov. Phil Bredesen opted to run. Bredesen lost by about 11 points to Republican U.S. Sen Marsha Blackburn.

Republicans have held both Tennessee Senate seats since 1994.