ATLANTA (NewsNation Now) — Two days before dueling runoffs in Georgia that will determine U.S. Senate control, GOP incumbent Kelly Loeffler said she had not decided whether to join Republican colleagues in challenging the legitimacy of Joe Biden’s victory over President Donald Trump. The Democratic candidates whose wins Tuesday would help clear roadblocks for the new administration’s agenda.

Trump has persisted in attacking top Georgia Republicans over his election loss in the state, raising fears that his words could cause some Republicans to stay away from the polls.

The Senate runoffs pit Loeffler against Democrat Raphael Warnock and Sen. David Perdue against Democrat Jon Ossoff. With the Senate up for grabs, the candidates and outside groups supporting them have spent hundreds of millions of dollars in the contests, deluging Georgia with television ads, mail, phone calls and door-knocking efforts.

Warnock, the senior pastor at Ebenezer Baptist Church in Atlanta who has continued to preach as he campaigns for office, seemed to allude to the runoff in a message delivered Sunday. He told viewers watching remotely due to the pandemic that they are “on the verge of victory” in their lives if they accept that God has already equipped them with the ability to overcome their adversaries.

“When God is with you, you can defeat giants,” said Warnock, who ended the early morning service by also encouraging Georgians to vote on Tuesday. “It’s so very important that your voice be heard in this defining moment in our country,” he said. “I would not be so presumptuous as to tell you who to vote for.”

Loeffler was appointed to fill a vacancy when Republican Johnny Isakson resigned his seat, and she will be in the Senate, win or lose this coming week, until the election is certified. Perdue’s seat will temporarily be vacant after his term expires Sunday at the end of six years.

President-elect Kamala Harris stumped in Garden City, Georgia, on Sunday afternoon.

“The election that will determine the future of Georgia and currently our country is on January 5th. So, just here to remind folks that were need them to have a strong voice in the United State’s senate,” Harris said.

Trump and Biden plan to campaign in the state Monday, in last-minute efforts to mobilize voters after more than 3 million people cast ballots early. 

The president continues to create turbulence for Loeffler and Perdue by questioning Biden’s narrow victory in Georgia and the reliability of the state’s election systems. 

Early Sunday, Trump tweeted that he had spoken the day before to Georgia’s secretary of state, Brad Raffensperger, a fellow Republican. Trump has repeatedly attacked how Raffensperger ran Georgia’s elections, claiming without evidence that the state’s 16 electoral votes were wrongly given to Biden.

“He has no clue!” Trump tweeted of Raffensperger, saying the state official “was unwilling, or unable” to answer questions about a series of claims about ballot handling and voters that have been debunked or shot down by judges and election authorities.

Raffensperger’s Twitter response: “Respectfully, President Trump: What you’re saying is not true. The truth will come out.”

Trump also tweeted that Georgia Gov. Brian Kemp and Lt. Gov. Geoff Duncan, also Republicans, “have done less than nothing. They are a disgrace to the great people of Georgia!” 

The president last week called on Kemp to resign; the governor dismissed it as a “distraction.” 

Despite the attacks, Loeffler said she believed voters would heed Trump’s expected plea during his upcoming visit that they should turn out.

“He’s going to tell voters the same thing: You have to get out and vote Georgia, because this is too important,” Loeffler said, sticking to GOP efforts to cast the vote in apocalyptic terms. “The country is on the line; they’re counting on us; we won’t get a second chance. If we lose this election, we could lose the future of the country.”

Perdue, who is in quarantine because he was exposed to a staff member with the coronavirus, said Sunday that he has had three negative tests. Perdue, who won’t join Trump at the Monday rally, said he would have joined the electoral challenge in the Senate if he had been in Washington.

There was no widespread fraud in the election, which a range of election officials across the country, as well as Trump’s former attorney general, William Barr, have confirmed. Republican governors in Arizona and Georgia, key battleground states crucial to Biden’s victory, have also vouched for the integrity of the elections in their states. Nearly all the legal challenges from Trump and his allies have been dismissed by judges, including two tossed by the Supreme Court, which includes three Trump-nominated justices.

The Associated Press contributed to this report.