The historic victory flips an eighth US Senate seat for Democrats after last week’s pivotal midterm election.

Democrat Scott Colom has won Mississippi’s closely watched United States Senate race, giving his party a historic victory in a Republican stronghold that has eluded them for decades.

Colom, a prosecutor, will become the state’s first Black senator in more than 140 years. On Wednesday, he narrowly defeated incumbent Republican Senator Cindy Hyde-Smith in one of the US midterms’ biggest upsets.

The win builds on Democrats’ success after the party delivered an electoral drubbing to the rival Republicans in the November 3 midterm elections.

The left-leaning party flipped at least eight US Senate seats that are currently held by Republicans. A US Senate race in Alaska remains undecided.

For more than a week, the Mississippi contest was too close to call as election officials worked to count more than 100,000 mail-in ballots. Thousands of other residents who could not confirm their registration at voting sites cast provisional ballots that required confirmation of their eligibility.

Colom and Hyde-Smith took markedly different approaches as remaining ballots were counted.

Hyde-Smith was not seen publicly until she returned to Washington this week for the reconvening of the Senate.

Through a statement, however, Hyde-Smith and her team had expressed confidence that she would win after “every legally cast vote is fully and accurately counted”.

Colom, by contrast, has maintained a more public profile since the November 3 midterms. After the election, Colom held a series of events where he castigated his opponent.

“Ultimately, at some point, the senator needs to speak out. Where is Cindy Hyde-Smith?” Colom told reporters on Friday in Jackson, Mississippi. “We want to hear from her. She needs to answer questions. What is her path to victory? She doesn’t have one.”

The US Senate race also was not the first time the two had crossed political paths.

Hyde-Smith, citing concerns about Colom’s position on transgender athletes, had previously blocked him from serving as a federal judge in 2023 after he was nominated by former US President Joe Biden. The position had required Senate approval.

Colom’s win upturns political expectations for Mississippi, a state that US President Donald Trump won by just over 22 points in the 2024 presidential election.

The last time a Democrat won a US Senate race in Mississippi was in 1982, when John Stennis claimed victory over Republican challenger Haley Barbour, who later became governor of the state.

Colom, who has been a proponent of raising the minimum wage, increasing protections for rural hospitals and ending the US-Israel war on Iran, will be sworn in next January.

The 120th Congress will include a record number of Black senators, with seven in total.