While Florida’s Treasure Coast backed Donald Trump in 2016, four years later Joe Biden has a chance to flip it. But the partisan dynamics at the top of the ticket in what was once Florida’s most competitive congressional district aren’t likely to topple incumbent Republican Rep. Brian Mast, who has spent the last four years focusing on environmental issues and characterizing himself as a moderate.

It’s a race between two veterans in a Republican-leaning district: Mast is the incumbent who is backed by Trump but also a well-known advocate for opposing discharges from Lake Okeechobee that fill rivers in his district with toxic blue-green algae. Former Naval judge advocate Pam Keith is a Black woman aligning herself with the hard left.

The race, where Mast is a heavy favorite, will likely come down to middle-of-the-road voters who can be persuaded to split their ballots for president and Congress.

Florida’s 18th Congressional District was redrawn in 2011 to include all of St. Lucie and Martin counties, along with a northern portion of Palm Beach County, where white people make up about 81% of the district’s population. It had previously been considered a swing district, but has remained in Republican hands since Democrat Patrick Murphy resigned to run for Senate and Mast won in 2016.

Political experts and analysts will be watching District 18 and its counties — especially St. Lucie County — on election night. Some believe the district will split the ticket, meaning voters will elect a representative from one party, and a presidential candidate from the other. This possibility is a reminder that the country isn’t completely divided and that there are still some swing voters out there, according to J. Miles Coleman, associate editor for Sabato’s Crystal Ball.

“We could very well see a situation where at the presidential level, it goes for Biden, but they stick with Mast down the ballot,” Coleman said. “And that would really be nothing out of line with how they voted in past years.”

Here’s why: More Democrats voted in the 18th District primary on Aug. 18 than in past primaries and the margins between Democratic and Republican voters were the closest they’ve been since 2016, indicating that the election on Nov. 3 could be close. Keith grasped about 80% of the vote against her Democratic opponent, but still remains significantly outraised by Mast.

The bigger Democratic turnout in the district, especially in St. Lucie and Palm Beach counties, also suggests that the district could vote for former Vice President Joseph Biden over President Donald Trump.

Split tickets have declined over the decades. In 2012, only 26 House districts split their votes, compared to 24 years earlier in 1988, when at least 145 House districts went one way for president and the other for representative. In 2016, 35 U.S. House districts had split tickets, including Florida’s 26th and 27th districts that voted for Hillary Clinton and Republican representatives.

FL-18 has split the ticket before, Coleman said, both in 2012 and again in 2014. In 2012, Mitt Romney won the district with 52% of the vote while Murphy, a Democrat, managed to win the newly drawn seat. Murphy kept his seat until leaving to run for Senate in 2016.

“Even though 2014 was sort of a red year overall, the Republicans picked up seats in the House, Florida 18 was something of an exception,” Coleman said.

The FL-18 election on Nov. 3 will likely come down to the swing voters, and both campaigns are painting the other candidate as extreme choices.

Mast’s campaign has been built on portraying him as the moderate choice while characterizing Keith as an extreme-left candidate.

Meanwhile, Keith’s supporters say she’s a passionate candidate capable of flipping the district.

“Being passionate does not make her extreme. Pam has a common-sense, ‘tell it like it is’ approach that voters of all parties respect,” Celeste Bush, chair of the St. Lucie County Democratic Executive Committee, said. “Brian Mast is an extremist who sides with Donald Trump — every time — over the people in his district.”

Mast, who lost both his legs and an index finger after stepping on an explosive device in 2010 in Afghanistan, is loved by many in the district, said Michael Barnett, chairman of the Palm Beach County Republican Executive Committee. Mast has focused much of his messaging toward moderate and independent voters, especially when it comes to issues like gun control and environmental issues.

Barnett said that while some extreme conservatives are displeased with some of Mast’s moderate stances, his alignment with President Trump carries his support from Republicans.

“The president has called him ‘my friend’ and he’s strongly backed Brian Mast,” Barnett said. “That’s helping Brian maintain his Republican and conservative credentials, while also doing what he needs to do to appeal to the folks moderate, in the middle, or may even be left leaning, may not support the president but will vote for Brian.”

His campaign spokesman Brad Stewart said that Mast would rather focus on bipartisan issues that matter to voters — especially moderate voters — more than national politics. He said the main issue Mast is focusing on over the next two weeks is clean water in the district.

“This is a district with a large portion of independent voters,” Stewart said. “You need to talk and appeal to the whole political spectrum.”

A TV ad launched by Mast for Congress in late August labeled Keith as a member of the “radical left” and a socialist, aligning her with Vermont Sen. Bernie Sanders, New York Rep. Alexandria Ocasio-Cortez and Minnesota Rep. Ilhan Omar.

“She has chosen to align herself with people who have extreme views,” Stewart said. “We’re going to point out those policies that we don’t believe align with the ideologies of voters in the district.”

Meanwhile, Democratic leaders in the district don’t see it as a partisan race and do not consider Mast a moderate candidate.

“While Brian Mast may position himself as a moderate, his record is not moderate,” Bush, chair of the St. Lucie County Democratic Executive Committee, wrote in an email.

Bush said that Keith is the right person to inspire voter turnout, especially among Democrats. She said she doesn’t think people will be splitting the ticket in FL-18 because people are turning away from Trump and candidates like Mast who’ve enabled him.

“What we are seeing on the ground is a massive turnout of Democrats standing up to a failed president,” Bush said. “A lot of voters will not see any difference between Mast and Trump.”

National Democrats, however, have stayed out of the race in 2020 after spending millions trying to flip the seat in 2018 and coming up about 9% short. That leaves Keith without millions of dollars in extra resources that typically go to incumbents and challengers in close races.

Keith said that any alignment with President Trump can’t be considered moderate. She said she hasn’t changed her platform since she ran in 2016, rather she believes the politics around her have changed rather significantly.

“What I believe to be fairly middle, has now become more left,” Keith said. “Not because I’ve moved left, but because the Republicans have moved right.”

Unlike Mast, Keith’s tactic this time around isn’t about appealing to middle voters. Instead she wants to inspire the left and drive Democratic voter turnout in the district. She said it’s hard to appeal to all things in this district, and it hasn’t worked for her or other Democrats in the past few election cycles.

“The prioritization was to appeal to the middle vote, assuming the left would come up, come to the polls out of partisan loyalty, but they don’t,” Keith said. “This time, I am doing so much better with the partisan base, the infrequent Dem, then the low propensity Dem, the new Dem. I’m doing so much better with that population, that I am much more in shooting distance.”

Keith is optimistic about her chances this year. She said that the climate with the Black Lives Matter movement and pandemic have set the stage for her supporters to show up. She said she still appeals to those middle voters by being intelligent, honest and confident.

Mast “is enabling and supporting the most monstrous person to ever occupy the White House, ain’t nothing moderate about that,” Keith said. “You cannot be a moderate Trumper. Sorry. You can’t be.”