Ketanji Brown Jackson, a liberal appeals court judge, was confirmed to the supreme court on Thursday, overcoming a rancorous Senate approval process and earning bipartisan approval to become the first Black woman to serve as a justice on the high court in its more than 200-year history.

After weeks of private meetings and days of public testimony, marked by intense sparring over judicial philosophy and personal reflections on race in America, Jackson earned narrow – but notable – bipartisan support to become the 116th justice of the supreme court. The vote was 53 to 47, with all Democrats in favor. They were joined by three moderate Republicans, senators Mitt Romney of Utah, Lisa Murkowski of Alaska and Susan Collins of Maine, who defied deep opposition within their party to support Joe Biden’s nominee. Their support was a welcome result for the White House, which had been intent on securing a bipartisan confirmation.

Jackson, who currently serves on the US court of appeals for the DC circuit, will replace Stephen Breyer, 83, the most senior member of the court’s liberal bloc. Breyer, for whom Jackson clerked early in her legal career, said he intends to retire from the court this summer.

At 51, Jackson is young enough to serve on the court for decades. Her ascension, however, will do little to tilt the ideological balance of the high court, dominated by a 6-3 conservative majority. But it does mean for the first time in the court’s history that white men are in the minority.

Kamala Harris, the first Black woman to serve as US vice-president, presided over the Senate vote as Jackson became the first Black woman to join the supreme court, underscoring the historic nature of her confirmation. Harris called for the final vote on Jackson’s nomination with a smile on her face, and the chamber broke into loud applause when the judge was confirmed.

“Today, we are taking a giant, bold and important step on the well-trodden path to fulfilling our country’s founding promises,” Senate majority leader Chuck Schumer said just before the final vote. “This is a great moment for Judge Jackson. But it is an even greater moment for America as we rise to a more perfect union.”

The White House has announced that Biden, Harris and Jackson will deliver remarks on Friday to celebrate the confirmation. Jackson and Biden watched the final Senate vote together in the Roosevelt Room of the White House.

Biden shared a photo taken with Jackson at the White House, saying on Twitter: “Judge Jackson’s confirmation was a historic moment for our nation. We’ve taken another step toward making our highest court reflect the diversity of America. She will be an incredible justice, and I was honored to share this moment with her.”

Assailing Jackson’s record, but acknowledging Republicans did not have the votes to stop her confirmation, minority leader Mitch McConnell implored the judge to embrace the textualist approach of conservative justices.

“The soon-to-be justice can either satisfy her radical fan club or help preserve the judiciary that Americans need, but not both,” McConnell said ahead of the vote on Thursday. “I’m afraid the nominee’s record tells us which is likely, but I hope judge Jackson proves me wrong.”

Her confirmation to the lifetime post represents the fulfillment of a promise Biden made to his supporters at the nadir of his 2020 campaign for president, when he vowed to nominate the first Black woman to the supreme court, if elected president and a vacancy arose. The opportunity presented itself earlier this year, at another low point for Biden, with momentous domestic and foreign challenges weighing on his presidency.

During the public hearings, Jackson vowed to be an independent justice who would seek to ensure that the words inscribed on the marbled supreme court building – Equal Justice Under the Law – were a “reality and not just an ideal”. With her parents and daughters present, Jackson recounted for the Senate judiciary committee her family’s generational journey, as the daughter of public school teachers raised in the segregated south who would rise to become a justice on a court that once denied Black Americans citizenship.

Yet any hope by the White House that Jackson’s historic nomination might defuse some of the bitter partisanship that senators lament has turned the process into a “circus” quickly evaporated.

With an eye to the November midterm elections, Republicans led an aggressive campaign against the judge during her confirmation hearings and in conservative media, raising questions about her record in an effort to paint her as an “activist judge” who is soft on crime. They used the confirmation proceedings to air conservative grievances about past supreme court nominations and to wage culture war battles over critical race theory, crime and transgender women in sports.

Couched in thinly coded appeals to racism and the far-right fringes with nods to the QAnon conspiracy theory, some Republicans accused Jackson of being too lenient on child sexual abuse offenders, claims she forcefully rebutted “as a mother and a judge”. Legal experts have said her decisions in such criminal cases were within the mainstream while independent factcheckers concluded that the attacks were misleading and a distortion of her record.

Democrats, and the handful of Republicans who supported her, praised her qualifications and demeanor, and in particular the restraint she showed during some stinging exchanges with conservative senators. They sought to defend her record, noting that her sentencing record was within the mainstream of the federal judiciary, while emphasizing the support she had earned from within the legal community, including among conservative justices, and her endorsement from the Fraternal Order of Police, which cited her family’s law enforcement background.

In a mark of just how polarizing the process of confirming a supreme court nominee has become, the Senate judiciary committee deadlocked along party lines over her nomination. The resulting tie prompted Democrats to execute a rare procedural maneuver to “discharge” her nomination from the committee to the floor, with a vote by the full Senate. The NAACP said the vote by 11 Republicans against Jackson’s nomination was a “stain” on the committee.

The final Senate vote on her confirmation was among the closest in supreme court history.

A graduate of Harvard and Harvard Law School, Jackson served on the independent US sentencing commission, an agency that develops sentencing guidelines, before becoming a federal judge.

While she shares an elite background with the other justices, her work as a public defender sets her apart. The last justice with experience representing criminal defendants was Thurgood Marshall, the towering civil rights lawyer who became the first Black member of the supreme court.