Our new book is titled Divided We Stand: The 2020 Elections and American Politics. Among other things, it discusses state and congressional elections.
In "Frankly, We Did Win This Election," Michael Bender wriates (p. 328):
Trump World sent word to Perdue’s campaign on October 29 that the president had agreed to a rally in Rome on November 1, just as the senator had requested. To ﬁt the Georgia stop into the schedule, which already included ﬁve rallies on each of the ﬁnal two days, the Trump campaign scratched one of two North Carolina events that day. But Trump had waited so long to commit to visiting Georgia that Perdue had to drop out of the ﬁnal debate— which had already been scheduled for that night—with his Democratic opponent, Jon Ossoﬀ, in order to attend the rally with the president.
In November, Perdue had a slight lead over Ossoff, with 49.7 percent of the vote. In any other state, that result would have been enough to elect him and ensure GOP control of the Senate. But Georgia requires a runoff when no candidate has an absolute majority. If Perdue had participated in the debate, he might have picked up just enough votes to reach 50 percent. In that case, there would still have been a runoff for the other seat. But without Senate control at stake, there would have been far less national Democratic involvement, and Loeffler might have held on. Thus, Trump's delay in visiting the state may well have denied the GOP a 52-48 majority.