WASHINGTON, July 10, 2024 (BSS/AFP) - With the pomp and pageantry of his official nomination just days away, Donald Trump's search for a running mate on the Republican presidential ticket is in the home stretch, with a trio of frontrunners jockeying to be first across the finish line.

The former US president is seeking a number two who can walk the delicate line between helping mobilize Trump's right-wing base and staying in lane as a sidekick who won't hog the limelight or, worse, prove more popular than the boss.

Trump is expected to make his choice public during next week's Republican National Convention in Milwaukee, with an announcement anticipated as early as the opening day on Monday.

The billionaire appears to have zeroed in on two US senators, J.D. Vance of Ohio and Marco Rubio of Florida, as well as North Dakota Governor Doug Burgum, who initially ran against Trump for the nomination before falling in line.

The calculus might yet change, as Trump told Fox News on Monday that he was weighing a "great bench" of prospects and had not made a decision.

"It's going to be a great vice president, meaning a person that can do a fantastic job as president, because you always have to think of that first," he said.

"And then, second, somebody that helps you get elected. And there's nothing wrong with that."

Ever the consummate showman, Trump has been ramping up the intrigue, sending out a "long list" of contenders early on and offering conflicting accounts of how far along he was in the selection process.

There was speculation that he might use his first public appearance in 11 days to announce Rubio as he addressed supporters at his Doral golf club, on the outskirts of Miami.

He namechecked the senator, who was in the front row, several times but was silent on his thinking for the veepstakes.

- Casting call -

Trump could have dropped his big reveal at any point in the days before Milwaukee, except that the news would have interrupted arguably one of the worst weeks in the career of his 81-year-old rival Joe Biden.

The veteran Democrat is facing calls to drop out of the race after a widely-panned debate performance against Trump raised questions about the mental capacity of America's oldest-ever president.

"The big danger right now is because all the attention is focused on Biden, that if you announce anything, it will get lost," Republican strategist Rob Burgess, who worked on the Trump 2016 and 2020 campaigns, told AFP.

One of the biggest factors for Trump will be his running mate's fund-raising prowess, and the contenders have all been under pressure to showcase their connections with wealthy mega-donors.

Meanwhile, the campaign has ensured that they are booked regularly for cable news interviews -- a kind of casting call that allows Trump to assess how they look in front of the cameras, a priority for the former reality TV star.

Trump said before the June 27 debate that he already knew who his running mate would be, noting that his pick would likely be attending that night.

The three frontrunners were all bused to the CNN studio in Atlanta along with some less-favored hopefuls to watch from a volleyball court before being sent in to pitch for Trump on the press line.

- Big role? -

Political analyst Donald Nieman said he expected Vance to get the nod as an articulate messenger for Trumpism who is seen as a draw for working class white men in the crucial swing states of Pennsylvania, Michigan and Wisconsin.

But he added that a less "thin-skinned" Trump might have been persuaded to go with Nikki Haley, a one-time UN ambassador who was his last-standing rival in the nominating contest.

"She would bring Republican defectors and suburban women to Trump -- something he needs," Nieman, a history professor at Binghamton University in New York state, told AFP.

"But he won't because she hasn't signaled abject loyalty and a willingness to submerge her own identity."

Haley, who says she is supporting Trump, has not been invited to the convention, according to Politico.

It remains to be seen in any case whether the successful candidate has what it takes to succeed where Mike Pence failed, and use the job as a springboard to the presidency.

"I'm not at all convinced that whoever Trump's vice president is, that he or she will have as significant a role as many of their predecessors," said constitutional expert Joel Goldstein, of Saint Louis University in Missouri.

"Although the vice president's role has grown, ultimately it depends upon the president's personality and his or her leadership style."