Senator Susan Collins of Maine plans to vote to confirm Judge Ketanji Brown Jackson to the Supreme Court, ensuring that President Biden’s nominee and the first Black woman to be put forward for the post will receive at least one Republican backer.

After a second personal meeting with the judge on Tuesday afternoon, Ms. Collins said Judge Jackson had alleviated some concerns that surfaced after last week’s contentious Senate Judiciary Committee hearings, when Republicans attacked the nominee for her record and grilled her on a host of divisive issues.

“I have decided to support the confirmation of Judge Jackson to be a member of the Supreme Court,” Ms. Collins said in an interview after the meeting.