U.S. President Joe Biden speaks at the 115th NAACP National Convention in Las Vegas, Nevada, U.S., July 16, 2024. / REUTERS/Tom Brenner/File Photo

REHOBOTH BEACH, Delaware/MILWAUKEE (Reuters) -President Joe Biden was "soul searching" about dropping his Democratic reelection campaign, a source said, while Donald Trump prepared to accept the Republican presidential nomination in what aides said would be an unusually reflective speech.

The fortunes of the two candidates appeared to be on opposite trajectories on July 18 in the run-up to the Nov. 5 election.

Biden, 81, was isolating at his Delaware home after contracting COVID-19 while facing a growing revolt from Democrats who urged him to step aside to avert a landslide defeat. His doctor said he was experiencing mild symptoms.

Trump, 78, has basked all week in adulation at the Republican National convention in Milwaukee after surviving a weekend assassination attempt at a Pennsylvania rally.

For the fourth consecutive night, Trump made a grand entrance into the arena during the program, still wearing a bandage over the ear that was wounded on July 13 and drawing huge applause.

Trump's acceptance speech, scheduled for 10 p.m. Eastern Time (0200 GMT on Friday), offers a chance to lay out his vision for a second White House term before a primetime national television audience.

Among the speakers on Thursday were the conservative commentator Tucker Carlson, former pro wrestler Hulk Hogan, and mixed martial arts impresario Dana White.

The head pro at Trump's Florida golf club, John Nieporte, praised Trump's skills on the course and claimed the former president had won 21 club championships.

"Joe Biden? Zero," he said, evoking the surreal moment from the June 27 presidential debate when Trump and Biden argued over which of the two candidates had a better golf game.

Biden has faced increasing pressure from heavyweights in his party to cede his position at the top of the ticket after his erratic performance on debate night. Former House of Representatives Speaker Nancy Pelosi is among those who have told him he cannot win in November, according to a White House source familiar with the matter.

After weeks of insisting that he will remain in the race, Biden is now taking calls to step aside seriously and multiple Democratic officials think an exit is a matter of time, according to sources familiar with the matter.

People close to the president told the New York Times on July 18 that they believe he has begun to accept the idea that he may have to drop out.

Democratic leaders in the House and Senate - Hakeem Jeffries and Chuck Schumer - have told Biden directly that he will not only lose the White House but also endanger their effort to win back the House, according to reports in multiple news outlets.

Opinion polls show four of the seven most competitive states looking increasingly out of reach for Biden. The Trump campaign, meanwhile, said it believes it is now competitive in Democratic-leaning states including Minnesota, New Hampshire, and Virginia.

Senator Jon Tester, who faces a challenging reelection battle in Montana this year, on July 18, became the 21st congressional Democrat and the second senator to publicly call on Biden to drop out.

Some lawmakers say Biden may now be more open to stepping aside.

"He's done what's best for America ... I think he'll keep doing so," Democratic U.S. Senator John Hickenlooper told Reuters. "He's working towards that."

Hickenlooper declined to say whether he believed Biden should step aside as a candidate.

Former President Barack Obama has told others that Biden, who was Obama's vice president, should rethink his candidacy, the Washington Post reported, citing anonymous sources.

REPUBLICAN UNITY

Trump will cap the four-day Republican convention with his first public address since the assassination attempt.

Lara Trump, the nominee's daughter-in-law who serves as Republican National Committee co-chair, said the attack had prompted him to revise his acceptance speech and emphasize unity.

"I don't think you can go through what he went through on Saturday, really a near-death experience, and not come out on the other side impacted," Lara Trump said.

Vice President Kamala Harris, who could vie for the Democratic nomination should Biden pull out, said Trump's call for unity would have little credibility, given his persistent refusal to acknowledge his 2020 election defeat.

"We're too busy watching what you're doing to hear what you're saying," she said at a campaign rally in Fayetteville, North Carolina.

With most dissent quelled and his grip on the Republican Party never tighter, Trump will be in a much stronger position than in his 2017-2021 term to follow through on his agenda if he wins the election.