Hyde-Smith, a Republican, faces Mike Espy, a Democratic former congressman and agriculture secretary, in Tuesday's runoff in MS - the final Senate race to be decided in 2018.
President Donald Trump, of whom Hyde-Smith has been a vocal supporter, will hold two rallies in MS on Monday to whip up support for the Republican candidate. Trump also has thanked her right back on Twitter for voting for "our Agenda in the Senate 100% of the time".
Meanwhile, Major League Baseball (MLB) is the latest organization to request a return of funds, saying it wants a $5,000 donation to her campaign.
This isn't the first time the league has made financial contributions to Hyde-Smith. She's up against Democratic former U.S. Rep. Mike Espy, a former U.S. agriculture secretary vying to become the first black senator from the state since Reconstruction.
The special election victor will serve the final two years of Cochran's term. President Donald Trump is set to travel to the state for two rallies with Hyde-Smith on Monday. Then they fly to the Gulf Coast for a rally in Biloxi.
On immigration, Trump defended the US response to the border clash on Sunday, when USA agents fired tear gas at migrants, some of whom had attempted to climb through fencing and wire separating the countries. "We need to come out tomorrow in such numbers, such strength, marching to the polls like it's a holiday", he said.
About 100 anti-Trump protesters were also there, chanting "Impeach 45" as they held signs with red strikes through Hyde-Smith's name. His campaign has focused more on issues such as social justice, health care and raising wages.More news: GM to slash jobs and production as United States sedan sales sink
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Trump was asked by a reporter about a comment in which she said she would be in the "front row" if she were invited to a "public hanging", a comment she later apologized for but said it had been twisted and weaponized by her opponents. She and her campaign have refused to discuss the Confederate hat.
The victor finishes the term of Sen.
The last two years of the Senate term begun by the now-retired Thad Cochran hangs in the balance Tuesday as voters decide between Republican U.S. Sen. Further digging into Hyde-Smith's past has revealed a photo of her wearing a Confederate military-style hat in 2014 along with questions about the white private school she attended in the 1970s.
Democrat Mike Espy spoke Saturday about how he and his twin sister were among the 17 black students who integrated the all-white Yazoo City High School in 1969, graduating in 1971.
About a third of MS voters were African-American in the four-way race on Election Day, and Espy won support from about 80 percent of them, compared to about 20 percent of white voters, according to VoteCast, a wide-ranging survey of the electorate conducted by The Associated Press.
Hyde-Smith's campaign called the school issue a personal attack on her family meant to draw attention away from real issues. More than 43,000 absentee ballots have been requested, and that number could increase as final numbers are tabulated. About 69,000 absentee ballots were requested before the 6 November election. There's typically a large decrease in ballots cast between the first election and a runoff. The state last elected a Democrat to the Senate in 1982.