Two sources familiar with Biden’s preliminary plans said the former vice president will announce his candidacy for the Democratic nomination for president on Wednesday in Charlottesville, Va., the site of a clash in August 2017 between white supremacists and counterprotesters that claimed one life.

Mr. Biden then will fly to Pittsburgh for a rally in the afternoon and then come to Philadelphia, where he will hold a rally at the Art Museum, though the sources said the plans have been shifting in recent days and could change again.

David L. Cohen, a Comcast senior executive vice president and an influential Democratic figure, is planning a fund-raiser for Mr. Biden at his Philadelphia home Thursday, one sign of the support the former vice president can expect from much of the party establishment, particularly in Pennsylvania.