After weeks of relative silence following a stroke that required urgent surgery, Senator Luján, Democrat of New Mexico, is back in Washington, D.C., and throwing his support behind President Biden’s nominee to the Supreme Court.

On Friday, the senator’s office released a statement applauding Mr. Biden’s nomination of Circuit Judge Kentanji Brown Jackson as Associate Justice on the court.

Mr. Luján described the nomination of a black woman to the court — a first for the nation — as a “long overdue step that will ensure the Court better reflects the American people.

“I look forward to working with my colleagues to ensure that Judge Jackson receives a fair and timely confirmation,” Mr. Luján said in the statement. “Judge Jackson was confirmed by the Senate with bipartisan support three times, and I am hopeful this time will be no different.”

Left unsaid in the statement, however, is exactly when Mr. Luján will be returning to the floor of the evenly divided Senate. Since Senate rules do not allow for remote voting, his presence in the chamber will be critical if Democrats fail to convince any Republicans to support Judge Jackson’s nomination to the high court.

Mr. Luján returned to Washington in the middle of February and was being treated at an area in-patient facility, according to videos posted to the senator’s Twitter account. On February 18, he said in a video that he was being released from that facility.

“Next stop is outpatient care and getting back to the floor of the U.S. Senate,” he said in the video. “Thanks for all the prayers everyone. We’ll see you soon.”

On February 1, Mr. Luján’s office shocked many of his colleagues and constituents when his chief of staff issued a statement saying the senator had checked himself into a hospital after suffering from a stroke in the cerebellum. The statement said the senator was expected to make a full recovery, but offered no further details.

Reports later emerged in New Mexico media outlets that the senator, who is 49 years old, underwent surgery to reduce the swelling in his brain. His office said he would need four to six weeks to recover.

Staffers told the Albuquerque Journal that his medical team would later make more information available, but nothing came out of his office until February 13, when a video of the senator seated next to two doctors was posted on Twitter. In the video, Mr. Luján said he felt strong and was confident of a full recovery.

“I’ll be back on the floor of the United States Senate in just a few short weeks to vote on important legislation and to consider a Supreme Court nominee,” he said in the video.

Days prior to the video’s release, Mr. Luján came under fire from open government groups in New Mexico for keeping his constituents in the dark about his condition and prospects. The New Mexico Foundation for Open Government described his absence from the Senate and his future service as issues of vital public interest and called on his office to lift the veil of privacy.

“While all of us respect the family’s wishes for privacy during this stressful time, a balance must be struck between that privacy and the public’s right to know,” the group said. “As every elected official can tell you, when you voluntarily step into the public sphere, you waive many of those privacy rights.”