Editor's note: This is the fifth in a series of profiles of potential running mates for presidential candidate Donald Trump on the 2024 Republican Party ticket
The race to determine who will be Donald Trump's running mate this November took a major step forward last week with the acceleration of vetting multiple potential candidates, but political insiders with deep knowledge of presidential campaigns say there is one possible name on the former president's shortlist Democrats "fear" the most.
Trump's campaign recently entered the next phase of the running mate search by requesting documents from several prospective contenders, including Florida Sen. Marco Rubio, who has grown to be a staunch ally of the former president since running against him in the 2016 Republican presidential primaries.
"Rubio is a familiar face who has become one of the strongest voices in the Senate for the America First agenda, is excellent on TV, and can blast Biden effectively for his failed policies," one top GOP strategist told Fox News Digital.
INSIDERS PREDICT THIS POSSIBLE TRUMP VP PICK POSES ‘EXISTENTIAL THREAT’ TO KEY AREA OD BIDEN SUPPORT
"Trump is doing very well with Latino voters and the addition of Rubio would only strengthen that, which could spell the end for Biden," they said, adding that "Rubio would be a solid, safe pick, with a lot of upside."
GOP strategist Matt Wolking, who served as deputy communications director for Trump's 2020 presidential campaign, described Rubio as "an effective, disciplined communicator who rarely makes mistakes."
He noted that Rubio was the only person under consideration who speaks another language, and that his ability to speak Spanish would help the Trump campaign reach Hispanic voters in many states where it could boost their competitiveness, including Nevada, New Mexico, Arizona, Virginia, New York, and Florida.
"While demonstrating his ability to win a slightly higher percentage of White voters in 2022 than Trump did in Florida in 2020, he also appeals to the suburban and independent voters that will be key to Trump’s success, and is the only contender from a true battleground state," Wolking said.
"Trump would balance out his ticket by picking Rubio for VP, which cannot be said for some of the other options. These reasons are why many Democrats fear the selection of Rubio the most," he said, citing a May Vanity Fair article specifically noting some of those worries.
INSIDERS PREDICT THIS ‘POWERHOUSE’ REPUBLICAN WOULD BRING MAJOR BOOST AS TRUMP VP PICK
Wolking added that Rubio's experience as a leader on the Senate Intelligence Committee would be "valuable" for Trump to "reign in rogue agencies."
A source close to Trump's campaign echoed what the other two said of Rubio's Latino heritage boosting the campaign's ability to connect with Hispanic voters, but also pointed to what they said were a few downsides to Rubio's potential selection.
"I'm not sure he's a 100% Trump guy. That's the one thing I would say, that he has not always been enthusiastic about Trump. I think that's the one area I would find could be a little troubling to the Trump faithful. That might be an issue," the source said.
They were noting Rubio's past criticism of Trump, including when he called him "reckless and dangerous" while running against him in 2016, and when he said the former president was responsible "for some of what happened" during the Jan. 6 protests at the U.S. Capitol.
"The other thing is the question of whether Rubio is the right person to carry the Republican colors in 2028 and beyond," the source said. "I think he's a good man. Don't get me wrong. I think he's been a great senator, and been very effective. I think he would be a more than adequate vice president, but it just gives me pause to think about him as a potential candidate, and whether he's a Trump-faithful follower."
EXPERTS REVEAL MAJOR ‘DOWNSIDE’ TO POTENTIAL TRUMP VP PICK: ‘NO WOW FACTOR’
Wolking, however, said none of the downsides to Rubio's selection were "particularly big ones," but noted he tends "to be more hawkish than Trump when it comes to foreign policy."
He also mentioned concerns over the Constitution's 12th Amendment, which prohibits electors voting for a president and vice president if they are inhabitants of the same state. Rubio and Trump are both residents of Florida.
"That would likely prove to be more a speedbump than a real obstacle to putting him on the ticket," Wolking said.
A source familiar with Rubio pointed Fox to the senator's positive performance in states like Virginia and Minnesota during his 2016 primary campaign, suggesting his selection could boost Trump in states now being viewed as potential targets for Republicans.
CLICK HERE TO GET THE FOX NEWS APP
The source also pointed to Rubio's legislative track-record, his debate performances during his two subsequent Senate re-elections since running for president, his ability to communicate, as well as his ability to "fire up a crowd" as all things that would make him a good addition to the Republican ticket.
A number of other big names have also been floated to join Trump on the Republican ticket, including House GOP Conference Chair Elise Stefanik, Arkansas Gov. Sarah Sanders, Virginia Gov. Glenn Youngkin, North Dakota Gov. Doug Burgum, South Dakota Gov. Kristi Noem, Ohio Sen. JD Vance and South Carolina Sen. Tim Scott.
Trump has suggested he will likely wait until July's Republican National Convention in Milwaukee to name his pick.
Fox News' Paul Steinhauser contributed to this report.