Grace Segers, CBS News

PHOENIX (CBS News/AP) – A liberal Florida Democrat pulled off an upset victory Tuesday in the state’s primary for governor while President Trump’s favored candidate cruised to victory for the GOP, setting up a fierce fall showdown in the nation’s largest political battleground.

Tallahassee Mayor Andrew Gillum, who would be the state’s first black governor, and Republican Rep. Ron DeSantis, both defeated opponents aligned with their parties’ establishments.

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U.S. Senate candidate Martha McSally speaks during her primary election night gathering on Aug. 28, 2018, in Tempe, Ariz. (Getty Images)

In Arizona, Rep. Martha McSally fended off a pair of conservative challengers to carry the Republican Senate primary to fill the seat vacated by retiring Sen. Jeff Flake. That race was shadowed by the death of John McCain, a towering figure who represented Arizona in the Senate for six terms. Gov. Doug Ducey will name McCain’s replacement after the senator’s funeral.

Though McCain has received praise from far and wide this week, the three Republican candidates running to replace his retiring seat-mate, Flake – including establishment favorite McSally – aligned themselves more with the president than the longtime senator.

Florida and Arizona are both closely watched states, featuring growing minority populations that have bolstered Democratic candidates and Republican electorates that have grown older and more conservative. The fall face-offs could well signal how they’ll swing in the 2020 presidential election.

In Florida, DeSantis gave Mr. Trump credit for his victory, saying that with one supportive tweet, the president “kind of put me on the map.” Gillum thanked supporters who embraced “our plan for a state that makes room for all of us, not just the well-heeled and the well-connected, but all of us.”

The results immediately transformed the Florida race into one of the key gubernatorial campaigns in the country. Gillum’s primary victory could help Democrats boost enthusiasm among minorities who often don’t vote in large numbers in years when a presidential candidate isn’t on the ballot. Meanwhile, DeSantis will test Mr. Trump’s grip on a crucial state he won in 2016 and wants to keep in his column in 2020.

DeSantis was one of several Republicans running in contests Tuesday in Florida and Arizona – another closely watched political battleground – who hoped that cozying up to the president would be rewarded by voters. The president has thrust himself into the forefront of the midterm campaign in hopes of motivating his supporters and offsetting Democratic enthusiasm.

Elsewhere Tuesday, GOP voters in reliably Republican Oklahoma backed mortgage company owner Kevin Stitt in a runoff for the gubernatorial nomination. Stitt won in part by criticizing his opponent as insufficiently supportive of Mr. Trump.

Arizona primary results

Senate race

Rep. Martha McSally, the preference of the national Republican establishment, easily won the Republican primary with 52 percent of the vote. Former state Sen. Kelli Ward and former Maricopa County Sheriff Joe Arpaio trailed behind McSally.

Rep. Kyrsten Sinema cruised to victory against her Democratic primary opponent, Deedra Abboud. National Democrats were hoping that Sinema would face Ward or Arpaio in the general election, as both of them are controversial right-wing figures considered to be more beatable. Sinema will have an uphill battle with McSally as an opponent.

Regardless of who wins in November, Arizona will be sending a woman to the Senate for the first time in state history.

Gubernatorial race

Incumbent Republican Gov. Doug Ducey easily dispatched his primary opponent, Ken Bennett, with 70 percent of the vote.

Democrat Doug Garcia, an educator and military veteran, won his primary against two opponents.

CBS News rates AZ-1 and AZ-2 as competitive congressional districts as Democrats seek to flip 23 Republican seats in the House this November. The 2nd Congressional District is the seat currently held by McSally, and is considered by Democrats to be a potential pickup in November.

Florida primary results

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Gubernatorial race

Trump-endorsed GOP Rep. Ron DeSantis won the race for governor, leading opponent Adam Putnam with 56 percent to 37 percent.

Mr. Trump tweeted his congratulations to DeSantis Tuesday night.

On the Democratic side, Tallahassee Mayor Andrew Gillum won the primary with 34 percent of the vote. Gillum and Gwen Graham were considered to be frontrunners in the Democratic primary.

If elected, Gillum would be the first black governor of Florida. He was one of the most progressive candidates in the primary, and is a staunch supporter of critical left-wing issues like Medicare for All and abolishing U.S. Immigrations and Customs Enforcement. Gillum was endorsed by Sen. Bernie Sanders.

However, the Democratic nominee is not untouched by scandal. The FBI is currently looking into corruption at Tallahassee City Hall, although Gillum, who is the mayor of Tallahassee, has not been implicated.

For House primaries, FL-18, FL-26 and FL-27 are the races to watch for potential Democratic upsets in November. Debbie Mucarsel-Powell won the Democratic primary in FL-26, and will face Republican Rep. Carlos Curbelo in November. Lauren Baer won the Democratic primary in FL-18, and will face Republican Rep. Brian Mast this fall. Maria Salazar won the Republican primary in FL-27, and will face Democrat Donna Shalala.

Senate race

In Florida, incumbent Sen. Bill Nelson runs uncontested. Gov. Rick Scott cruised to victory in the Republican primary. Mr. Trump also wrote a congratulatory tweet for Scott.

Recent polling shows Scott leading Nelson by a few points. An August poll by Florida Atlantic University had Scott at 44 percent and Nelson at 39 percent.

Oklahoma governor runoff

Former Oklahoma City Mayor Mick Cornett won the gubernatorial runoff against Gateway Mortgage Company founder Kevin Stitt with 55 percent of the vote.

In the Libertarian primary for governor, Chris Powell quickly outpaced Rex Lawhorn, taking nearly 60 percent of the vote.

CBS News’ Jack Turman contributed to this report.

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