Because of the grip he maintains on conservative voters, what Mr. Trump says in Valdosta on Saturday and beyond may prove decisive in Georgia. If he makes an emphatic case for Mr. Perdue and Ms. Loeffler, and portrays a Senate Republican majority as a crucial check on perceived Democratic excesses, it could rally enough conservatives to ensure two Republican wins next month.
“The best thing they can do, those who supported Trump, is to support his legacy by having the Senate come back with a Republican majority,” said Senator Thom Tillis, Republican of North Carolina, articulating the message G.O.P. lawmakers hope Mr. Trump delivers.
Yet Mr. Trump is refusing to even acknowledge he lost and every day is sowing distrust in Georgia’s voting system as he takes to Twitter to cry falsely that the election was “rigged.” He has repeatedly railed against the vote-counting machines the state used and falsely asserted that mail-in ballots were rife with fraud, giving Republicans reason to question both voting by mail and in-person voting.
“The senators’ best argument is that Georgia needs to elect them to be a check and balance on President Biden,” said Whit Ayres, a veteran Republican pollster. “The problem is, President Trump won’t let them make that message. And it puts the Senate candidates in a real bind.”
If Mr. Trump veers from his teleprompter on Saturday and in subsequent trips here to dispute his 12,000 vote loss and lashes out at Mr. Kemp and Secretary of State Brad Raffensperger, it could overwhelm his scripted message and undermine the intended purpose of his visit by convincing his supporters that their votes may not count in January.
Compounding the challenge for Republicans, and to the great joy of Democrats, the president has been joined in his promotion of conspiracy theories by a pair of far-right lawyers, Sidney Powell and L. Lin Wood. But Ms. Powell, who until recently was part of Mr. Trump’s legal team, and Mr. Wood have gone even further, arguing that Georgia Republicans should punish the party by boycotting the Jan 5 runoffs.
If even a modest number of Republicans sit out the election, especially in rural areas where Mr. Trump’s support is strongest, it could be enough to alter the electoral math in this evenly divided state and tip the two races to the Democrats.