ATLANTA — The allies of Stacey Abrams, the Democratic candidate trailing in the Georgia governor’s race, hit the streets and the phones on Friday in a vigorous last-minute push to get anyone who cast a provisional ballot to ensure that their vote would count, in the hopes of forcing the close, bitter and expensive contest into a runoff.

It was a dramatic and unorthodox political effort, a kind of post-campaign campaign to give Ms. Abrams the chance to go into a Dec. 4 overtime round with Brian Kemp, her Republican adversary.

Earlier this week, Mr. Kemp declared victory in the race and argued that no math could bring his total to less than 50 percent, which would automatically force a runoff. Mr. Kemp currently has 50.3% of the 3.9 million total votes cast, leading Ms. Abrams by about 63,000 votes.

President Trump, who has endorsed Mr. Kemp, declared him the victor on Twitter Friday. “It is time to move on!” he said.