Incumbents defeated by the largest margin

A defeat counts when the person who won the previous regular general election for a seat ran in the next one and lost it. Senate seats are grouped by class and governorships by state, so the seat being defended is the same seat; special elections are excluded, and a gap of more than one term in a seat’s record ends the chain rather than inventing an incumbent. Three further conditions keep the list to real head-to-head defeats. The beaten incumbent must have finished second, with at least 5% of the vote: the largest raw margins otherwise belong to a different story entirely, an incumbent who had already lost the nomination and ran on anyway to finish third, or, in Minnesota in 2002, a senator who had died eleven days before the election. The winner must be the recorded winner, not merely the vote leader. And the top two must have drawn 50,000 votes between them, the same floor the other margin rankings use. One contest is set aside as a primary filed as a general: 1910 Georgia records Hoke Smith against the sitting governor Joseph M. Brown, both Democrats, both totals round to the thousand, in a race where Smith was in fact unopposed in November.