Donald Trump is currently holding a rally in Charlotte, North Carolina -- his first since Biden dropped out of the race.

The former president quickly turned his focus to Harris, claiming she is "the ultra-liberal driving force behind every single Biden catastrophe."

"You know, I was supposed to be nice," Trump said. "They say something happened to me when I got shot, I became nice. And when you're dealing with these people, they're very dangerous people. When you're dealing with them, you can't be too nice. You really can't be. So, if you don't mind, I'm not going to be nice."

"The defense of democracy is more important than any title," Biden will say in his prime-time address tonight, according to excerpts released by the White House. "I draw strength, and find joy, in working FOR the American people. But this sacred task of perfecting our Union is not about me. It’s about you. Your families. Your futures. It’s about 'We the People.'"

He will go on to praise America as a place where "kings and dictators do not rule" -- perhaps a subtle jab at Donald Trump, who once remarked he would be a dictator only on "Day 1" if elected to a second term.

"The great thing about America is here, kings and dictators do not rule. The people do," Biden will say. "History is in your hands. The power is in your hands. The idea of America – lies in your hands."

-ABC News' Molly Nagle

In his Oval Office address later this evening, Biden will discuss his decision to withdraw from the 2024 race and endorse Vice President Kamala Harris.

"I have decided the best way forward is to pass the torch to a new generation. That is the best way to unite our nation," he will say, according to excerpts of his speech released by the White House.

He will also reiterate his commitment to seeing out the remainder of his term.

"Over the next six months I will be focused on doing my job as president," he will say. "That means I will continue to lower costs for hard-working families and grow our economy. I will keep defending our personal freedoms and our civil rights – from the right to vote – to the right to choose."

-ABC News' Molly Nagle

Kamala Harris' virtual presidential nomination could start Aug. 1, but may be pushed back if other qualified candidates jump in the race

The Democratic National Convention's Rules Committee voted 157-3 on Wednesday to adopt a plan that allows the party to start its virtual presidential nomination process as soon as Aug. 1.

While Harris secured commitments from enough delegates to become the presumptive nominee if they all honor their commitment when voting, according to ABC News reporting, the plan approved on Wednesday allows for other candidates to jump in the race. They have from Thursday, July 25, until Saturday, July 27, at 6 p.m. ET to toss their names in the ring.

After filing a declaration of intent, all potential candidates will need to qualify to be considered for the nomination by filing a formal and notarized declaration of candidacy with the DNC, meeting party and legal qualifications to be president, and securing 300 delegate signatures electronically, not more than 50 of which may come from one delegation, according to the committee. The window to submit qualification materials ends on Tuesday, July 30, at 6 p.m. ET.

The rules adopted on Wednesday state that if only one candidate for nomination reaches the delegate support threshold to be considered by the convention, electronic voting by the delegates will begin on Aug. 1.

There is no set end date to virtual voting, but the rules committee said it should be completed "by early August."

-ABC News' Isabella Murray, Oren Oppenheim and Jacob Steinberg