Democrats hope the vote, scheduled for 12:20 p.m. will pressure Republicans to allow debate to begin on the bill amid election-year pressures and widespread anger at Wall Street.
The time has come to move this conversation from the sidelines to the playing field, Reid said on the Senate floor.
Republicans have so far united to block action as they seek a compromise. One key moderate, Republican Susan Collins, said on NBC's Today Show that she again planned to vote against it.
With the two parties locked in a stalemate on the Senate floor, the Republicans have floated a counterproposal that could propel the two sides toward common ground on the most ambitious rewrite of Wall Street rules since the Great Depression.
(Reporting by Andy Sullivan and Tabassum Zakaria, editing by Jackie Frank)