Former Vice President Joe Biden told at least a half-dozen supporters Tuesday he intends to run for president and asked for their help in lining up contributions from major donors so he can quickly raise several million dollars, a person familiar with the matter said.

Mr. Biden has expressed concern to these people that he wouldn’t be able to raise millions of dollars in online donations immediately the way some other Democratic candidates have, including former Rep. Beto O’Rourke of Texas and Sen. Bernie Sanders of Vermont, this person said. Mr. O’Rourke raised $6.1 million in the 24 hours after he launched his bid for the Democratic presidential nomination, while Mr. Sanders collected $5.9 million in the same period.

Mr. Biden wants to announce a large fundraising number after his candidacy is official to better compete in what is often dubbed the “money primary” that kicks off a presidential season.

Mr. Biden has indicated previously that he is close to entering the race, but he hasn’t yet reached a final decision, with people around him cautioning that he could change his mind. A spokesman for Mr. Biden declined to comment Tuesday.

The former vice president’s team is scouting out a location for his campaign headquarters. Philadelphia, which is about 30 miles away from Mr. Biden’s home in Wilmington, Del., is the leading contender, according to a second person familiar with the discussions. The person said that the location of the headquarters hadn’t been finalized.