Tennessee Three member Gloria Johnson to challenge Sen. Marsha Blackburn in 2024

State Rep. Gloria Johnson, one of the Tennessee Three lawmakers who Republicans sought to expel from office, announced Tuesday she is running for the U.S. Senate.

Why it matters: Johnson is harnessing her newly enhanced national profile to challenge incumbent U.S. Sen. Marsha Blackburn, a pro-Trump conservative firebrand, in 2024.

Reality check: Tennessee Democrats have not come close to winning a Senate seat since Harold Ford narrowly lost to Bob Corker in 2006.

• Even two-term former Democratic Gov. Phil Bredesen failed to get within shouting distance of the GOP. He lost to Blackburn in 2018 by just under 11 points.

Zoom in: Johnson was a battle-tested politician before she and fellow Democratic state Reps. Justin Jones and Justin Pearson drew the ire of Republicans during the spring legislative session.

• Both parties have intensely contested Johnson's Knoxville-area legislative district.
• She won her state House seat in 2012 before losing in 2014 and 2016. In 2018, she knocked off incumbent Rep. Eddie Smith to regain her seat, which she still holds.

Earlier this year, Johnson joined Jones and Pearson in a protest on the House floor to express frustration with the lack of willingness to take up gun reform legislation after the Covenant school mass shooting. Republicans said the protest broke protocols and voted to expel Jones and Pearson. Johnson survived an expulsion vote.

What she's saying: Johnson, a retired teacher, cast herself as a political outsider in a campaign video coinciding with her announcement. She put the fallout from Covenant and the ensuing debate around gun reform at the forefront of her pitch.

• "When my friends and I believed mothers and fathers who lost children at Covenant deserved a voice and we fought for it, they expelled them," she said in the video.

• "Most importantly, we deserve a leader with the courage to stand up to extremists and billionaires that have taken over our system," Johnson said. "That person ain't Marsha Blackburn."

The other side: Blackburn's campaign clapped back, calling Johnson a "radical socialist."

• "State Rep. Johnson is as woke as they come, and she would be a puppet for Joe Biden, the Squad, and Chuck Schumer in the Senate," a spokesperson for Blackburn's campaign said.

Editor's note: This story has been corrected to attribute a quote regarding State Rep. Gloria Johnson to a campaign spokesperson for U.S. Sen. Marsha Blackburn, not Sen. Blackburn.