Democrats Set to Take Control of Congress as Mississippi Senate Upset Triggers Washington Showdown

Democrats are preparing to take control of both chambers of Congress in January following a series of midterm victories, including a historic upset in Mississippi that helped break Republicans' longstanding hold on the state's Senate seat.

NBC News projects Democrat Scott Colom defeated Republican incumbent Sen. Cindy Hyde-Smith in a closely contested race, making Colom Mississippi's first Black U.S. senator since Reconstruction.

Colom's victory marks the eighth Senate seat Democrats have flipped in the midterm elections. His win also adds to the party's expected majority in the Senate, with one race still being counted.

"I respect the decision of Mississippi voters," Hyde-Smith said following the loss.

Colom celebrated the victory, emphasizing that the historic result was a collective effort.

"It's not something that I did, y'all. It's something that we did," he said.

Democrats are expected to use their new congressional majorities to focus on affordability, government accountability and investigations into the Trump administration.

That prospect is already creating tension between congressional Democrats and the White House.

White House Counsel Will Scharf sent a warning letter to Rep. Robert Garcia, the California Democrat expected to lead the House Oversight Committee when Democrats take control in January.

The letter warned that congressional investigations conducted for improper political purposes could cross legal boundaries and potentially result in investigations by the executive branch.

Scharf's warning signals an escalating confrontation over congressional oversight and the scope of investigations Democrats plan to pursue.

Garcia pushed back, saying Democrats would not be intimidated from conducting oversight of the administration.

"Donald Trump is clearly hiding something. We're not going to be threatened or intimidated because we are demanding accountability and oversight," Garcia said.

The political developments come as Defense Secretary Pete Hegseth faces additional scrutiny following a Veterans Day incident at Arlington National Cemetery.

An effort to advance articles of impeachment against Hegseth was effectively defeated in the House Tuesday after lawmakers voted 211-204 to send the resolution to committee.

The following day, Hegseth and members of his entourage were reprimanded by an Army sentinel guarding the Tomb of the Unknown Soldier.

Video showed Hegseth, his wife and senior Pentagon officials taking photographs near the memorial. As members of the group were heard talking and laughing, the sentinel called out a reminder that visitors must maintain an atmosphere of silence and respect.

The Tomb of the Unknown Soldier is one of the nation's most solemn military memorials, honoring unidentified American service members who died in war.

A Pentagon spokesperson said the secretary and the department would always honor the sacrifices of American military personnel, adding that the soldier appropriately reminded visitors to maintain proper decorum.

With Democrats preparing to take control of Congress, the coming months are expected to bring increased scrutiny of the Trump administration and potentially contentious battles between Capitol Hill and the White House.

NBC News correspondent Alice Barr reports from Washington.