The nine-term senator was a main sponsor of the law, which would restrict abortions as early as six weeks, and helped secure its passage in the chamber. Democrats have vowed political payback, and some Hollywood powers have threatened to pull investments from Georgia because of the measure.
She will become the most prominent Republican in a crowded field. Other Republicans include former Home Depot executive Lynne Homrich, ex-NFL running back Joe Profit and physician Rich McCormick. State Rep. Todd Jones appears likely to run, while military veteran Harrison Floyd recently dropped out.
The winner will face one of a tide of Democrats. Carolyn Bourdeaux, who lost to Woodall by less than 500 votes, is running again. So are state Rep. Brenda Lopez, attorney Marqus Cole, former Fulton Commission chair John Eaves and party organizer Nabilah Islam.
It’s not clear if Unterman will resign her state Senate seat to run, but her departure would leave the chamber with only one Republican woman: Kay Kirkpatrick, a physician who represents an Atlanta-based district.
First elected to the Senate in 2002, Unterman quickly became one of the most influential Republicans under the Gold Dome. She served six years as head of the Senate Health Committee after serving a decade as its vice-chair, playing a role in every major healthcare policy debate.
She forged a deeply conservative record, voting for gun rights expansions and "religious liberty" legislation. Long before the "heartbeat" measure surfaced, Unterman backed proposals that banned abortions after 20 weeks of pregnancy and required abortion providers to give women information about alternatives.
Her campaign will likely emphasize her more bipartisan initiatives, such as stiff new crackdowns on sex trafficking, requirements that insurance companies should be made to cover autism treatment for young children and efforts to target opioid abuse.
Her opponents will surely highlight her provocative statements and knack for courting controversy. She and Kemp's campaign traded intensely personal barbs during last year's heated GOP runoff; Unterman was a top ally of Lt. Gov. Casey Cagle and one of his more prominent surrogates.
And she became a punching bag for TV host Samantha Bee after she blocked legislation in 2016 to require the processing of thousands of rape kits. She relented minutes before the legislative session gaveled to the close, though she criticized Democrats for using the "issue as a wedge."
After she was demoted from her powerful healthcare post early this year, Unterman lashed out at her GOP colleagues - and offered a public apology to Kemp for their clash. With oversight only over a minor committee, she was effectively sidelined in the new Republican regime.
That changed with the emergence of House Bill 481, which aims to outlaw most abortions as soon as a heartbeat is detected. After a fraught debate in the House led by many male supporters of the legislation, Republicans turned to Unterman to shepherd the bill through the Senate. It passed on a party-line vote.
She also circled back on the rape kit measure, teaming with Democrats in the House to pass legislation that preserved sexual assault evidence indefinitely until cases are solved.
Unterman's budding Congressional campaign has been an open secret for months, and she's already taken shots at Homrich on social media, complete with the hashtag "#fakecampaign."
Democrats, meanwhile, have long prepared for her to jump in the race.
Avery Jaffe of the Democratic Congressional Campaign Committee accused her of putting “special interest backers ahead of working families” and criticized her support of abortion restrictions “to advance her own political agenda.”