President Biden’s decision to bow out of the November election leaves a path for Vice President Kamala Harris to replace him that would have seemed unlikely for most of the last three years, when she was seen as a drag on his reelection prospects as her approval numbers in polls lagged behind her boss’.

But Democratic desperation and Harris’ own recent performance as a vigorous administration spokesperson and loyal deputy have changed her fortunes. If she receives the nomination, Harris would be the first woman of color to head a national ticket and, if she wins, the first female president.

Several recent polls show Harris is now in close striking distance, within one or two percentage points, in a head-to-head matchup against former President Trump. Republicans, preparing for a possible Harris candidacy since Biden’s poor debate performance in June, have been resurfacing old clips of her, mocking her sometimes awkward public speaking style, blaming her for “covering up” Biden’s frailty and tying her to the high number of arrests at the southern border that have occurred under Biden’s watch.

Many anxious Democrats have clamored for other candidates, including Govs. Gretchen Whitmer of Michigan, Gavin Newsom of California or Josh Shapiro of Pennsylvania — worrying that Harris remains too polarizing a figure to win a majority of voters.

She has ground to make up against Trump and her national approval rating, while improved, remains at about 39%, compared with 50% of voters who don’t approve of her, according to the latest 538 polling average. She also has ground to make up in swing states, according to polls.

But Harris, 59, has the advantage of experience on a national ticket, direct access to the campaign’s fundraising apparatus and name recognition, all of which make her a favorite to secure what will be an unprecedented nomination for whoever wins it. She can also run on the administration’s policy accomplishments, which Democrats believe are popular even if Biden, 81, is not.

“The advantages vice presidents have is they have depth and reach,” said Elaine Kamarck, a Democratic delegate and author of “Primary Politics: Everything You Need to Know about How America Nominates Its Presidential Candidates.”

Biden’s opinion carries weight. But once he releases his delegates, they would be unbound by his wishes, meaning any number of candidates can try to win a majority of more than 4,500 voting party delegates. In his letter Sunday, he praised Harris as an “extraordinary partner.”

He endorsed Harris in a subsequent tweet.

“My very first decision as the party nominee in 2020 was to pick Kamala Harris as my Vice President,” he wrote. “And it’s been the best decision I’ve made. Today I want to offer my full support and endorsement for Kamala to be the nominee of our party this year. Democrats — it’s time to come together and beat Trump. Let’s do this.”

Another advantage for Harris is that many delegates have said they are eager for a smooth process, given the chaotic preceding weeks. Whoever wins the nomination would also have to choose a running mate in time for the convention, likely from among the same group of contenders for the top slot.

Despite Harris’ built-in advantages, someone else could certainly make a race of it, added Kamarck, a Brookings Institution think tank fellow who served as an aide to former Vice President Al Gore.

Harris, born in Oakland to immigrants from Jamaica and India, has had a steady rise through Democratic politics, from elected district attorney of San Francisco to California attorney general to U.S. senator and then vice president. She now resides in Los Angeles when she is not staying at the vice president’s official residence at the Naval Observatory in Washington.

Harris came into the 2020 presidential primary with massive expectations, touted by many in the party as the fresh face of the future, only to see her campaign falter before votes were cast amid staff infighting and a sense that Harris lacked core ideological convictions. She had trouble, for example, explaining her position in the universal healthcare debate that was a defining issue for progressives.

Biden, by selecting her as his running mate, reinvigorated her political career. She proved an able campaigner in a supporting role. But as vice president, she experienced high staff turnover and had to vie with Biden’s longtime aides — some of whom were suspicious of her after she attacked Biden in the 2020 primary — for influence. As the first Black and Indian American woman in national office, she also contended with racial and gender prejudices.

Her top early assignment from Biden, to curb migration by improving conditions in Central America, became a political headache as she tried to dodge responsibility for the record numbers of migrants stopped at the border and stayed away from policy debates on Capitol Hill.

During a 2021 trip to Guatemala and Mexico, she told migrants, “Do not come,” angering the left, and then laughed off questions about why, at the time, she had not yet visited the border, igniting the right. The early impression was a setback given the relatively few opportunities vice presidents have to command the public’s attention.

Harris improved her standing with the party in 2022, when the Supreme Court overturned the legal right to an abortion and Harris became the administration’s leading voice in opposition, helping Democrats overperform in the 2022 midterm elections. She also began traveling abroad more, representing Biden in Europe amid Russia’s invasion of Ukraine and in Asia as part of a broader strategy to counter Chinese influence.

Unlike other vice presidents, who had time to settle into the job during their first term, Harris was immediately under pressure to show she could step in for Biden, the oldest president in American history, said Joel Goldstein, an expert on vice presidents. She was also a rarity in the modern age, when most vice presidents have had more government experience than their boss.

“If Vice President Harris becomes sort of the determined standard-bearer for 2024, I think that she’ll have a visibility and importance and people will look at her in a way that they haven’t looked at her previously,” Goldstein said.

She will need the second look. In focus groups, many voters say they don’t know what she does. And she polls similarly to Biden among key constituencies in recent surveys conducted by Suffolk University’s David Paleologos for USA Today.

Harris was viewed favorably by 30% of independents and unfavorably by 57% in a national poll taken after the debate in late June, compared with a 35%-62% split for Biden.

Polls of Black and mixed-race voters in Michigan and Pennsylvania — two battleground states — taken in early June showed only 55% to 60% of those voters viewed her favorably, similar to Biden’s numbers. He and Harris won more than 90% support from Black voters in 2020, according to exit polls.

Paleologos said Harris has a little more room to grow support compared to Biden, but it’s still an uphill climb.

“Kamala Harris could generate excitement, maybe not to the level of what Trump has,” he said. “That’s a big deficit right now.”