Barnes withdrew from the race as the Milwaukee Journal Sentinel was preparing to report that the state Democratic Party last year reviewed anonymous allegations about his sexual encounters.
Two Republicans, who are set to leave the Senate next year, are insisting that the president’s IRS deal must be rewritten before they will vote for the nominee.
Left-leaning candidates have been gaining strength in recent primaries, posing challenges for a Democratic Party that is debating how to win mass appeal in 2028.