Cindy Hyde-Smith (R) was sworn in on Monday to fill the seat vacated by former Sen. Thad Cochran William (Thad) Thad CochranEspy wins Mississippi Senate Democratic primary Bottom Line Mike Espy announces Mississippi Senate bid MORE (R-Miss.).

Vice President Pence administered the oath on the Senate floor to Hyde-Smith, who was formerly Mississippi’s commissioner of Agriculture and Commerce.

Fellow Mississippi Sen. Roger Wicker Roger Frederick WickerHillicon Valley: DOJ indicts Chinese, Malaysian hackers accused of targeting over 100 organizations | GOP senators raise concerns over Oracle-TikTok deal | QAnon awareness jumps in new poll Shakespeare Theatre Company goes virtual for 'Will on the Hill...or Won't They?' Republican Senators raise concerns over Oracle-TikTok deal MORE (R) accompanied Hyde-Smith, as did GOP Sens. Orrin Hatch Orrin Grant HatchBottom line Bottom line Senate GOP divided over whether they'd fill Supreme Court vacancy MORE (Utah), Lamar Alexander Andrew (Lamar) Lamar AlexanderGraham: GOP will confirm Trump's Supreme Court nominee before the election The Hill's Morning Report - Sponsored by Facebook - Washington on edge amid SCOTUS vacancy This week: Supreme Court fight over Ginsburg's seat upends Congress's agenda MORE (Tenn.) Susan Collins Susan Margaret CollinsGraham: GOP will confirm Trump's Supreme Court nominee before the election Gardner signals support for taking up Supreme Court nominee this year Tumultuous court battle upends fight for Senate MORE (Maine) and Majority Leader Mitch McConnell Addison (Mitch) Mitchell McConnellGraham: GOP will confirm Trump's Supreme Court nominee before the election Trump puts Supreme Court fight at center of Ohio rally The Memo: Dems face balancing act on SCOTUS fight MORE (Ky.), along with Minority Leader Charles Schumer Chuck SchumerJacobin editor: Primarying Schumer would force him to fight Trump's SCOTUS nominee CNN's Toobin: Democrats are 'wimps' who won't 'have the guts' to add Supreme Court seats Republican senator says plans to confirm justice before election 'completely consistent with the precedent' MORE (D-N.Y.).

Pence and Hyde-Smith are also expected to take part in a mock swearing-in from the old Senate chamber.

ADVERTISEMENT

Hyde-Smith was appointed to the Senate seat after Cochran resigned on April 1 following four decades in the chamber.

Cochran announced his decision to retire last month, saying his health had became an "ongoing challenge" and he wanted to step down with enough time to ensure a "smooth transition" to his successor.

Cochran, who ran the Appropriations Committee, marked the third Senate committee chairman to announce his decision to retire or resign this year. GOP Sens. Bob Corker Robert (Bob) Phillips CorkerHas Congress captured Russia policy? Tennessee primary battle turns nasty for Republicans Cheney clashes with Trump MORE (Tenn.) and Hatch, who oversee the Foreign Relations and Finance committees, respectively, are retiring after 2018.

Mississippi Gov. Phil Bryant (R) announced late last month that Hyde-Smith, a former Democrat who joined the GOP in 2010, would temporarily fill Cochran’s seat.

Hyde-Smith is the state’s first female senator and brings the total number of women in the Senate to 23 — an all-time high for the chamber.

Under Mississippi election law, a special election will be held in November for the remainder of Cochran’s term, which runs through 2020. If no one receives 50 percent of the vote, the top two candidates would then compete in a runoff.

Cochran’s retirement has shaken up Mississippi’s political scene.

Chris McDaniel, a conservative firebrand who unsuccessfully challenged Cochran in 2014, was running against Wicker in this year’s midterms but announced in March that he will run for Cochran’s seat instead.

Republicans are growing concerned that Cochran’s retirement could threaten their ability to keep his seat in the “R” column.

Hyde-Smith has close ties to the Trump administration and was reportedly considered for the role of Agriculture secretary after serving as a co-chair on President Trump Donald John TrumpBubba Wallace to be driver of Michael Jordan, Denny Hamlin NASCAR team Graham: GOP will confirm Trump's Supreme Court nominee before the election Southwest Airlines, unions call for six-month extension of government aid MORE's Agriculture Advisory Committee during his presidential campaign.

But White House officials reportedly told Bryant that Trump would not endorse Hyde-Smith if she runs in November, fearing her past as a Democrat could be a ballot box liability.

Internal Republican polling showed Hyde-Smith behind both McDaniel and a Democratic candidate.