WASHINGTON—David Perdue, one of two Republican senators facing a runoff election in Georgia next week, is quarantining after coming in contact with someone who tested positive for the coronavirus, his campaign said on Thursday. Perdue (R-Ga.) was notified on Thursday he was in “close contact” with someone on his campaign who was infected with the virus, a campaign statement said, adding that Perdue and his wife tested negative. The quarantine threatens to disrupt the final days of campaigning ahead of the Jan. 5 contest that will determine whether Republicans or Democrats control the Senate. Perdue attended a campaign event on Wednesday in Hiawassee, Georgia, where he met with supporters. In photos of the event, he and others can be seen wearing masks and standing close together. Perdue posted a photo of himself and his wife on Twitter Thursday night and said the couple was feeling “great” and planned to ring …