Former Georgia Lt. Gov. Geoff Duncan is running as a Democrat for governor

FILE - Former Georgia Lt. Gov. Geoff Duncan speaks during the Democratic National Convention, Wednesday, Aug. 21, 2024, in Chicago. (AP Photo/J. Scott Applewhite, File)

ATLANTA (AP) — Former Republican and onetime Georgia Lt. Gov. Geoff Duncan is running as a Democrat for governor, a remarkable step for a staunch critic of President Donald Trump who left the conservative fold in a region where party switchers have gone in the other direction for generations.

“I’ve never wavered in taking on Trump. So Georgia Republicans threw me out of their party," Duncan said in his announcement video released Tuesday. “I was leaving anyway. Now I’m running for governor as a proud Democrat.”

A 50-year-old resident of a Republican stronghold north of Atlanta, Duncan joins an already crowded field of lifelong Democrats. Top candidates include former Atlanta Mayor Keisha Lance Bottoms, state Sen. Jason Esteves and former labor commissioner Michael Thurmond.

Duncan pitches himself as the most electable Democrat in a state that still leans slightly Republican. On policy, he plans to focus on health care access and cost-of-living issues. And he plays up his opposition to the GOP's Trumpian turn.

“I’m running for governor to put Georgians in the best position to once again love their neighbors," he said. “And to make Georgia the front line of democracy and a backstop against extremism.”

Duncan won the state's second-highest office in 2018 after one term in the state House. He ran in the shadow of now-Gov. Brian Kemp, who narrowly defeated national Democratic star Stacey Abrams. Two years later, Democrat Joe Biden eked out a victory in a state Republicans had dominated for two decades. Kemp and other key Georgia Republicans spurned Trump's efforts to overturn the 2020 results, but Duncan was maybe the most outspoken opponent, punishing state senators who backed Trump's efforts.

Kemp endured opposition from Trump, thrashing a Trump-endorsed challenger in the 2022 GOP primary on his way to again defeating Abrams. But Duncan opted against a reelection bid to instead become a paid CNN contributor as a former elected Republican who opposed Trumpism. The state GOP formally excommunicated Duncan in January, saying that acts including speaking at the 2024 Democratic National Convention in favor of Vice President Kamala Harris meant Duncan “forfeited any claim to being even a nominal ‘Republican.’”

Some of Duncan's policy stances as lieutenant governor may appeal to Democrats, like helping broker a state hate crimes law and supporting improvements to foster care. But a candidate who boasted in 2018 of being “100% pro-life” is likely to face sharp questions about his support of a 2019 state law that bans most abortions. Duncan also backed a Republican overhaul of Georgia election law after victories by Biden and two Democratic senators. It tightened absentee voting regulations and reduced the use of ballot drop boxes.

When he finally joined Democrats in August, Duncan explained his shift in moral terms as much as political terms.

“As I got elected starting in 2013 as a state representative, and then as lieutenant governor, it just became so hard at times to try to figure out the right way to do the right thing, as a Republican,” Duncan told NPR affiliate WABE.

He cited GOP opposition to tighter gun regulations and expansion of Medicaid health insurance as examples of Republican orthodoxy he could no longer support.

The question for Duncan is whether he can corral enough Democratic votes to win the nomination. He has spent years since leaving office without a political home.

Georgia Republicans remain enthralled with Trump — demonstrated by the fact that Duncan’s successor as lieutenant governor is Burt Jones. Now running for governor, Jones declared himself a “duly elected and qualified” elector for Trump in 2020. Jones also pushed for a special session in Georgia aimed at overturning Biden’s narrow win in the state.

In neighboring Florida, former Republican Gov. Charlie Crist made a comeback bid as a Democrat in 2022. He won the Democratic nomination but lost the general election by double digits to Republican Gov. Ron DeSantis.

Unlike Florida's meandering Democratic Party, Georgia Democrats have a bench of statewide candidates.

Duncan's advisers and allies highlight his stumping for Harris. But Bottoms, the former Atlanta mayor, also backed Harris and earlier worked in Biden's West Wing.

They tout Duncan's relative youth, but Esteves, an up-and-coming lawmaker, is even younger at 42.

They hold up his experience as a former legislator who has won statewide office. But Thurmond, 72, has been a legislator, won statewide three times as Georgia labor commissioner and ran the school system and county government in DeKalb County. That Atlanta suburb is a Democratic bastion. Thurmond, like Duncan is also appealing to moderates and even some conservatives who can't stomach Trump.