Lynch is planning to address voters in Dewey Square, across from South Station on Wednesday.
Dewey Square was also the site of the Occupy Boston protests in late 2011.
Lynch is squaring off against fellow Congressman Edward Markey in the April 30 Democratic primary in the special U.S. Senate election.
Two Republican Senate candidates are also hitting the campaign trail on Wednesday
GOP hopeful Daniel Winslow is planning a press conference on the steps of the Statehouse at 10:45 p.m. to announce some endorsements. Fellow Republican Senate candidate Gabriel Gomez has scheduled two stops in Wilmington.
The special election is June 25.