History and a handful of issues threaten the Democrats’ narrow congressional majorities in next year’s midterm elections.

Even though President Joe Biden’s job approval ratings remain solid if unspectacular, standing at 52.6% in the RealClearPolitics polling average and 51.3% in FiveThirtyEight’s, the first midterm election has tended to go against the president’s party since the 1930s. But Democrats are facing major headwinds beyond past precedent as they seek to hold on to their 50-50 split in the Senate — only Vice President Kamala Harris’s tiebreaking vote gives them control — and nine-vote margin over Republicans in the House.