President Donald Trump on Monday inserted himself into a searing racial debate here in the cradle of the Confederacy, barnstorming Mississippi on the eve of a Senate runoff election riven by divergent attitudes here about the legacy of segregation and lynching.

With his forceful and unambiguous endorsement of Republican Sen. Cindy Hyde-Smith - whose embrace of Confederate traditions and comments about a "public hanging" have revived painful memories of Mississippi's dark history - the president again dived into a cultural firestorm.

By yoking himself with Hyde-Smith, Trump is backing a politician who said she would sit with a supporter in the front row of a public hanging, donned a Confederate uniform to promote tourism at Jefferson Davis's homestead, and graduated from one segregation academy while sending her daughter to another.

"Race is always the key in which life in Mississippi is played," said Stuart Stevens, a Republican strategist and Mississippi native who wrote a book about growing up here. "It's just always present and it is the greatest determinant, still, in Mississippi of one's path through life."

Trump's decision to swoop into Mississippi aboard Air Force One on Monday to stage two campaign rallies - one here in Tupelo and the second in Biloxi - on the eve of Tuesday's runoff election underscored the uncertain state of Hyde-Smith's candidacy.

The president was on a rescue mission to mobilize his supporters around the incumbent senator, who was appointed by Gov. Phil Bryant, R, to fill a vacancy earlier this year left by the retirement of Sen. Thad Cochran, R. Republican strategists privately say Hyde-Smith has stumbled badly and struggled to generate momentum, though they are confident that she ultimately will prevail.

Hyde-Smith has cast herself as a Trump clone. She has hopscotched the state on a campaign bus emblazoned with a massive picture of her and the president together and dubbed "The MAGA Wagon," a play on Trump's "Make America Great Again" campaign slogan. She brags that she has voted with Trump "100 percent of the time," including to confirm Supreme Court Justice Brett Kavanaugh. On issue after issue, from trade to immigration, she parrots the president's talking points.

Still, the contest is far more competitive than had been expected in solidly Republican Mississippi, a state Trump carried in 2016 by 18 percentage points. After Hyde-Smith's hanging remark, public and private polls have measured a boost in voter enthusiasm for Democratic Senate candidate Mike Espy, who is black and has made racial discrimination a central theme in the campaign's closing weeks.

Neither Trump nor Hyde-Smith made any overt mention of the racial controversies surrounding the race when they rallied a crowd of several thousand people bundled up against the cold as the sun set on the airport tarmac here in Tupelo.

The president called Tuesday's runoff "one of the most important elections of your lives," and he cast Hyde-Smith as a champion of his agenda who would bolster the Republican majority in the Senate.

"She votes to make America great again and she votes for America first," Trump said, referring to two of his slogans. "Cindy is so important, so respected, we've got to send her back. If we win tomorrow, we'll be at 53-47."

Hyde-Smith, meanwhile, emphasized her traditionally conservative ideology, saying she would work to lower taxes, loosen regulations, support the military and law enforcement, and fight for antiabortion policies.

"I will stand up for your conservative values and that is what's on the ballot tomorrow," Hyde-Smith said.

Espy, a former congressman and an agriculture secretary in the Clinton administration, has embraced his position as an underdog. He told reporters on Monday that he planned to speak at a gospel event while Trump is campaigning with Hyde-Smith.

"We welcome him to Mississippi," Espy said. "He's going to say whatever he has to say, and we're going to be praising the Lord."

As voters head to the polls on Tuesday, the question is whether Mississippians will retreat to their natural partisan alignment or whether, as occurred in neighboring Alabama a year ago, enough suburban Republican voters break with their party to deliver a Democratic upset.

Hyde-Smith and her allies are banking on the former, and they are hopeful that Trump's visit reminds voters that she would be a rubber stamp on his agenda.

"I don't have any doubt that Mike Espy will vote with [House Democratic Leader] Nancy Pelosi and Cindy Hyde-Smith will vote with President Trump, and at the end of the day that's why Cindy Hyde-Smith will win," said Henry Barbour, a Mississippi-based Republican strategist who runs Mississippi Victory Fund, a super PAC helping Hyde-Smith.

Last December in Alabama, also a staunchly Republican state, Democrat Doug Jones won a special election to the Senate in the wake of credible allegations that GOP nominee Roy Moore harassed and assaulted underage girls when he was in his 30s.

Trump defended Moore against the allegations, campaigned for him and ordered the Republican National Committee to maintain its support for his campaign, even as other GOP figures and groups - including the National Republican Senatorial Committee - pulled their support.

Although a majority of white voters backed Moore, Jones prevailed by boosting turnout among African Americans and other loyal Democrats, as well as among suburban whites who lean Republican but rejected Moore.

"The question is, have white folks' attitudes changed in Mississippi?" Democratic strategist Paul Begala said. "In Alabama, they have. The winning message for Doug Jones was, 'Don't embarrass us, Alabama.' But I just don't know. It is still Mississippi."

Hyde-Smith's supporters say it would be wrong to compare her candidacy to Moore's.

"Cindy Hyde-Smith made an awkward comment and didn't clean it up fast enough," Barbour said, compared with the accusations against Moore.

Hyde-Smith has defended her hanging comment as an exaggerated gesture of friendship, but many interpreted her remark as an allusion to lynching.

In the candidate's only debate for the runoff, Hyde-Smith delivered a limited apology and said that her remarks had been "twisted" for political purposes.

"For anyone that was offended by my comments, I certainly apologize," she said. "There was no ill will or intent whatsoever in my statement."

Espy replied, "I don't know what's in your heart, but we all know what came out of your mouth. It's given our state another black eye that we don't need. It's just rejuvenated old stereotypes that we don't need anymore."

Just as he did with Moore, Trump came to the senator's defense when a reporter asked Monday night in Gulfport, Mississippi, whether Hyde-Smith's hanging remark was appropriate.

"First of all, there was an apology made," Trump said. "I heard that loud and clear. Second of all, really it was something that was sad and it was a little flip. . . . I know where her heart is, and her heart is good. That's not what she was meaning when she said that."

The Senate race has turned into a proxy of sorts for a debate over the identity of Mississippi. Once the lynching capital of America, Mississippi is the last state in the union still incorporating the Confederate battle flag in its state flag. But the state has also been striving to modernize, and has sought to reckon with its white supremacist past by opening a new state history and civil rights museum under the same roof in Jackson.

Hyde-Smith's campaign has proved toxic in some quarters. AT&T, Walmart and some other major corporations have moved to distance themselves from the senator by publicly requesting that their donations be returned.

Elise Jordan, a Mississippi native who served in the George W. Bush administration and is now a Republican commentator, wrote in an op-ed in the Clarion Ledger that the election is "about the values we want our great state to represent in the world."

"I know that many Mississippians worry about sending a Democratic senator to Washington, but I worry more that Cindy Hyde-Smith, who gave only a belated and cursory apology for comments supporting voter suppression and, of all things, public hangings, will be a constant reminder of the darkest days of our history," Jordan writes. "Is that a reputational risk Mississippians can afford to take?"