Chants of "fight" popped up during the roll call -- a nod to Trump, who could be seen mouthing "fight" and pumping his fist as he was taken off the stage following Saturday's assassination attempt.

Following Delaware's pledging of their votes to Trump, members of its delegation raised their fists in the air and chanted "fight, fight, fight!"

Wyoming delegates have done the same.

Idaho Republican Party chairwoman Dorothy Moon, while announcing delegates for Trump, led delegates in chanting "fight, fight, fight!"

-ABC News' Jacob Steinberg and Tommy Barone

Trump has officially cleared the numerical threshold at which he has locked in the nomination, with a pause in the roll call for celebration.

Florida, his adoptive home state, put him over the edge as his son, Eric Trump, announced the delegates.

-ABC News' Tommy Barone

Donald Trump Jr. played a key role in his father picking Ohio Sen. J.D. Vance as his running mate.

Sources tell ABC News the former president's son "led a strong push" for him behind the scenes and that Trump made his decision in the last few hours.

Trump Jr. told ABC's Rachel Scott on the RNC convention floor he was "incredibly excited."

"J.D's become a really good friend … his story is an incredible one, the American dream."

"I know the man, I know the character," Trump Jr. said of his friend, J.D. Vance.

-ABC's John Santucci and Rachel Scott

The roll call vote to select Trump as the nominee is in progress, after the former president was formally nominated by Iowa GOP chair Jeff Kaufman and Nevada GOP Chair Michael McDonald.

"We want to remind all our delegates, alternates and guests that maintaining order during the roll call is extremely important," House Speaker Mike Johnson said.

In his speech, Kaufman said that over the next four days, they will hear about Trump's "broad and inspiring vision for our country."

"This is not a program just for Republicans, but one for all Americans," he said.

In his speech, McDonald played up Trump's support for eliminating taxes on tips -- a policy that plays well in the service-industry-dependent swing state of Nevada.

"In Nevada, a state that is resilient on service industry. President Trump has proposed to eliminate taxes on tips on day one," McDonald said. "Unlike the Biden-Harris administration and the Democrats that increased taxes on tips."

As Iowa cast its votes, Iowa GOP chair Kaufman gave a shoutout to basketball star Caitlin Clark, while Sen. Mike Lee of Utah shouted out JD Vance -- Trump's just-revealed VP pick -- as he announced the state's delegates for Trump.

-ABC News' Oren Oppenheim