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.