Blackburn overcame a primary challenge from Tres Wittum, a former Tennessee legislative staffer who placed last in the 5th Congressional District primary in 2022. Blackburn first won the Tennessee Senate seat in 2018, defeating Democratic former Gov. Phil Bredesen by almost 11 percentage points.

On the Democratic side, state Rep. Gloria Johnson is hoping to advance to face Blackburn in November. She became nationally known after Republican lawmakers tried to expel her over a gun control protest, but came up a vote short despite kicking out two of her Democratic colleagues. She faces Memphis community activist Marquita Bradshaw, who notably won the Democratic Senate nomination in 2020 then lost to Republican Bill Hagerty by a wide margin. Two other Democrats are in the running: Civil Miller-Watkins and Lola Denise Brown.

Tennessee has solely elected GOP statewide candidates for nearly two decades. Blackburn also heads into the fall campaign with a significant edge in campaign cash over any of the Democrats.

THIS IS A BREAKING NEWS UPDATE. AP's earlier story follows below.

NASHVILLE, Tenn. (AP) -- Tennessee's primary election Thursday will decide whether state Rep. Gloria Johnson, who shot to national fame after surviving a Republican-led expulsion effort for her participation in a gun control protest, will become the Democratic nominee in a fall matchup for the seat held by Republican U.S. Sen. Marsha Blackburn, who must first clear her own primary contest.

The primary will also determine whether Republican Rep. Andy Ogles will be able to defeat a well-funded opponent, Nashville council member Courtney Johnston, as he pursues a second term in Tennessee's 5th Congressional District.

In the Senate race, Johnson faces Marquita Bradshaw, a Memphis community activist and organizer who notably won the Democratic Senate nomination in 2020 then lost to Republican Bill Hagerty by a wide margin. Other Democrats running are Civil Miller-Watkins and Lola Denise Brown.

Last year, days after a school shooting that killed three children and three adults, Johnson joined fellow Democratic Reps. Justin Pearson and Justin Jones as they walked to the front of the state House floor with a bullhorn. The trio joined the chants and cries for gun control legislation by protesters in the public galleries and outside of the chamber.

The trio were quickly dubbed the "Tennessee Three" as they soon faced expulsion hearings for violating House rules. Pearson and Jones, who are both Black, were expelled then later returned to office, while Johnson, who is white, was spared by one vote. Shortly after the expulsion vote, Johnson quickly noted that she avoided expulsion likely because she was white. Republicans denied race was a factor.

Whoever advances out of the Democratic primary will be running in a state that has solely elected GOP statewide candidates for nearly two decades.

Blackburn first won the Tennessee Senate seat in 2018, defeating Democratic former Gov. Phil Bredesen by almost 11 percentage points.

Tres Wittum, a former Tennessee legislative staffer who placed last in the 5th Congressional District primary in 2022, is the only Republican running against Blackburn.

Blackburn headed into the primary with almost $8.8 million in cash on hand, a significant fundraising edge. Johnson had more than $2 million available after raising about $5 million since entering the race.

Meanwhile, Ogles has earned the backing of former President Donald Trump. Yet his opponent, Johnston, is hoping that Ogles has irked enough Republicans by creating headaches over questions about his resume, inaccurate campaign finance reporting and a headline-grabbing approach to lawmaking.

Johnston has outraised Ogles in campaign contributions, although Ogles had slightly more in the bank as of mid-July.

Ogles first won the congressional seat in 2022 after Tennessee Republicans redrew the district to include a part of left-leaning Nashville.

Since his election in 2022, Ogles has been a vocal critic of the Biden administration and last year filed articles to impeach President Joe Biden and Vice President Kamala Harris. He filed new articles to impeach Harris after she became the front-runner for the Democratic presidential nomination following Biden's exit from the 2024 race.

The winner will face Democrat Maryam Abolfazli in the fall.

In the state legislature, about half of the state's 33 Senate seats and all 99 House seats are up for election this year. Republicans currently have supermajorities in both chambers. And the incumbent U.S. House lawmakers are all seeking reelection.