It’s time! Do it!
Louis C. Wyman (R-New Hampshire) was declared the victor of the US Senate contest in 1974 in New Hampshire by a narrow margin on Election Day (355 votes).
A first recount gave the election instead to John A. Durkin (D-New Hampshire) by ten votes, but a second recount swung the result back to Wyman by only two votes. The state of New Hampshire certified Wyman as the winner, but Durkin appealed to the Senate, which had a sixty-vote Democratic majority.
The Senate refused to seat Wyman while considering the matter. After a long and contentious debate in the Senate, with Republicans filibustering attempts by the Democratic majority to seat Durkin instead, a special election was held, with Durkin winning handily and becoming Senator.
https://en.wikipedia.org/wiki/Unseated_members_of_the_United_States_Congress