WILMINGTON, Del. — Joseph R. Biden Jr. has told allies that he has interviewed every finalist in his vice-presidential search, and his advisers are planning an announcement for the middle of the week, people briefed on the selection process said on Monday.

In a sign that the choice is now in Mr. Biden’s hands alone, the four-member committee that screened his potential running mates is said to have effectively disbanded — its work is complete, Biden allies said, and there is little left to do except for Mr. Biden to make up his mind.

Mr. Biden’s political team has prepared rollout plans for several of the finalists, and he is expected to announce his decision as soon as Tuesday, though more Democrats expect it to come on Wednesday. The former vice president, however, has not been known for his punctuality so far in the presidential race and the timeline could well slip again.

Mr. Biden has spoken with the vice-presidential candidates through a combination of in-person sessions and remote meetings over the last few weeks, but the exact timing and circumstances of all of the meetings are not clear. Close advisers to Mr. Biden said he had been directly in touch with all of the leading candidates.

Some of the strongest contenders have been Senator Kamala Harris of California; Susan Rice, the former national security adviser; Senator Elizabeth Warren of Massachusetts; and Gov. Gretchen Whitmer of Michigan, who met with Mr. Biden on Aug. 2. Mr. Biden and his team have also closely considered Senator Tammy Duckworth of Illinois, Gov. Michelle Lujan Grisham of New Mexico and Representatives Karen Bass of California and Val Demings of Florida.

All of them were interviewed by Mr. Biden’s search team, a panel of advisers and party luminaries informally led by former Senator Christopher J. Dodd of Connecticut.

The final days of the search, like everything else in this race, have been shaped by the coronavirus. While some of the conversations have been in person, others have taken place over the phone, according to Democrats familiar with the process.

Mr. Biden spent time this weekend in Rehoboth Beach, Del., where his family has a beach house, and on Monday addressed a virtual fund-raiser with Muslim American leaders from his Wilmington home, located in a verdant neighborhood that showed signs of recent storm damage. He was not, however, asked about his vice-presidential selection, according to a news media pool report from the event.