Joe Manchin, the West Virginia Democrat who had been the lone member of his caucus to oppose his party's more sweeping overhaul -- known as the For the People Act -- which passed the House earlier this year.
The other Democratic senators who are co-sponsors include Sens.Jeff Merkley of Oregon, Tim Kaine of Virginia, Jon Tester of Montana, Alex Padilla of California and Raphael Warnock, the Georgia freshman who faces a potentially tough reelection fight next year.