As the grand spectacle of his official nomination approaches, Donald Trump's quest for a running mate on the Republican presidential ticket is nearing its conclusion, with three leading candidates vying to be the first to cross the finish line.

The former US president is looking for a deputy who can balance the fine line of energizing Trump's conservative base while maintaining a supportive role that doesn't overshadow him or, even worse, become more popular than him. Trump is anticipated to reveal his choice at the upcoming Republican National Convention in Milwaukee, possibly as early as Monday, the opening day.

The billionaire seems to have narrowed his focus to two US senators, J.D. Vance of Ohio and Marco Rubio of Florida, along with North Dakota Governor Doug Burgum, who initially competed against Trump for the nomination before aligning with him. Trump mentioned in an interview with Fox News that he is considering a 'great bench' of prospects and has not yet made a final 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 stated. 'And then, second, somebody that helps you get elected. And there's nothing wrong with that.'

Trump, known for his flair for drama, has heightened the suspense by releasing a 'long list' of potential candidates early and providing conflicting accounts of his progress in the selection process. There was speculation that he might announce Rubio during his first public appearance in 11 days at his Doral golf club near Miami, where he frequently mentioned the senator in the front row but remained silent on his VP choice.

Trump could have made his big announcement any time before the Milwaukee convention, but the timing would have risked overshadowing arguably one of Joe Biden's worst weeks in his political career. The 81-year-old Democrat is facing calls to withdraw from the race following a poorly received debate performance against Trump, which raised concerns about his mental fitness.

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

One significant factor for Trump will be his running mate's ability to raise funds, and the contenders have been under pressure to demonstrate their connections with major donors. Additionally, the campaign has scheduled them for frequent cable news interviews, allowing Trump to evaluate their on-camera presence, a priority for the former reality TV star.

Before the June 27 debate, Trump indicated that he already knew his running mate, noting that his pick would likely be present that night. The three frontrunners, along with other hopefuls, were gathered at the CNN studio in Atlanta to observe from a volleyball court before being invited to pitch their case to Trump on the press line.

Political analyst Donald Nieman suggested that Vance might be chosen for his ability to articulate Trumpism and appeal to working-class white men in key swing states. However, he noted that a less 'thin-skinned' Trump might have considered Nikki Haley, a former UN ambassador and his last-standing rival in the nomination contest, who could attract Republican defectors and suburban women.

Haley, who supports Trump, has not been invited to the convention, according to Politico. It remains uncertain whether the chosen candidate can succeed where Mike Pence failed and use the position as a stepping stone 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.