The speech will be a pivotal moment for Abrams, who narrowly lost last year's gubernatorial race to Republican Brian Kemp and refused to formally concede the race, citing what she said was a vote marred by irregularities and his refusal to step down as the state's top elections official.
In the weeks since her defeat, she's launched a well-funded voting rights group to carry her message and challenge GOP policies in court, joined a Washington think tank and organized a "thank you" tour that started last week in the southwest Georgia town where she kicked off her campaign for governor.
“At a moment when our nation needs to hear from leaders who can unite for a common purpose, I am honored to be delivering the Democratic State of the Union response,” she said on social media.
More: Stacey Abrams is under intense pressure to run for Senate
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Abrams, who becomes the first black woman to deliver the address, will dramatically elevate her profile at a time when Democrats are trying to keep core liberal supporters engaged and mobilized as the crowded race for president starts to form.
It's also seen as the latest sign that she is more likely than not to challenge U.S. Sen. David Perdue, setting up a blockbuster matchup against a first-term Republican and former Fortune 500 chief executive who is one of Trump's most dependable allies.
When asked about Abrams’ address, Perdue said he looked “forward to hearing President Trump’s message to the American people.”
“One thing I’ll guarantee is that you’ll see a stark contrast between what President Trump is going to describe as the future direction of our country and what the radical left is talking about right now,” he said through a spokeswoman.
Abrams is the most influential Democrat in Georgia, and her endorsement is coveted by presidential candidates who see the state as a battleground. An Atlanta Journal-Constitution poll released this month showed Perdue's favorability ratings at about 45 percent — roughly 7 percentage points behind Abrams.
She gave herself a March deadline to announce whether she will run for Senate in 2020 and met recently with Schumer to discuss the race, and other potential Democratic candidates are deferring to her - or openly calling for her to enter the race.
"I am running for office again," Abrams told a crowded room of supporters at the start of her tour last week. "I don't know for what."
Republicans, who have long tried to depict Abrams as an out-of-touch career politician, mocked the decision to pick a candidate who recently lost a statewide contest. Ellie Hockenbury of the Republican National Committee said it was part of Abrams’ “never-ending pursuit of the public limelight.”
“While Chuck Schumer may feel her agenda would be a good fit for national Democrats,” she said of Abrams, “it’s worth remembering that it wasn’t even a good fit for her fellow Georgians who rejected her bid for governor just last year.”
Trump was originally scheduled to deliver the State of the Union on Jan. 29, but House Speaker Nancy Pelosi refused to sign off on the speech during the government shutdown. He will now address a joint session of Congress from the House chamber on Feb. 5.
Abrams will be the first non-sitting public official to deliver the State of the Union rebuttal since the tradition began in 1966. Abrams stepped down from the Georgia Legislature, where she was the House’s top Democrat, to run for governor in 2017.
The national platform will require a policy shift for Abrams. Over the last two years, she kept her attention squared almost entirely on state issues and rarely uttered Trump's name aloud during the campaign, even after the president endorsed her opponent.
But she had previously started a "Georgia Resists" website through her House caucus devoted to challenging Trump's policies shortly after he took office, and described the president as "just the fuel we needed to accelerate our progress."
There's little doubt that Abrams is on Trump's radar. Shortly after her defeat, Trump tweeted that the Democrat had a "terrific political future" - but he had nothing positive to say about her before that moment.
He told reporters in Washington she's "not qualified" to be Georgia governor. And at a rally in Macon, he claimed that her victory will have "Georgia turn into Venezuela" and called her one of the "most extreme, far-left politicians in the entire country."
“She wants to raise your income tax very substantially, she wants to raise your property tax very substantially,” Trump falsely asserted, adding “she supports a socialistic takeover of health care.”
The rebuttal gig is seen as a launching pad for rising political stars. Then-Congressmen Gerald Ford and George H.W. Bush earned national notoriety by delivering the GOP responses to President Lyndon Johnson’s speeches in the late 1960s.
But it's also a much-scrutinized assignment that some have dubbed the "worst job in politics."
U.S. Sen. Marco Rubio, R-Fla., was ridiculed for his 2013 counter-address, not because of his policy points but an awkwardly timed water break. Bobby Jindal’s profile plummeted in 2009 after the Louisiana governor’s televised response to President Barack Obama was mocked as cheesy and uninspired.
And much of the coverage generated from Rep. Joe Kennedy’s speech last year focused on his glistening lips, not his criticism of Trump.
Schumer, in the interview, said he’s confident that Abrams will rise to the occasion.
“I couldn’t think of a better choice. We were sitting around thinking about this three weeks ago, and her name came up,” he said. “Immediately, everyone in the room said, ‘Let’s do it.’”