President Trump winning a second term should put Vice President Mike Pence on a path toward the 2024 nomination.

Despite his unstinting — his critics say craven — loyalty, all the signs are, it won't.

Other Republicans with their eyes on the White House in 2024 show no inclination to defer to him while party insiders scoff at the notion he might be a shoo-in.

Pence, 59, is a trusty soldier working tirelessly to re-elect his boss — historically the surest path to the next nomination for ambitious vice presidents who serve eight years. But top Republicans say Pence is no heir apparent. The vice president has not demonstrated his mettle on the national stage by differentiating himself from Trump or built a separate power base that might discourage challengers.

“He has to prove he can stand the big spotlight in a primary to be trusted as the nominee in the general election. It’s nothing personal, just political prudence,” a Republican eyeing a future White House bid told the Washington Examiner, requesting anonymity in order to speak candidly. More than a dozen well-placed Republicans were interviewed for this story, all of whom declined to criticize Pence without the shield of anonymity. The vice president’s political team declined to comment for this story.

Pence faces additional hurdles that are, ironically, a unique product of the success he’s shared with Trump — not least of which is that the victory of the Trump-Pence ticket in 2016 upended the Republican Party’s practice of playing next-in-line politics to choose nominees.

And Trump has altered the ideological trajectory of the GOP, a dynamic that could leave the vice president caught in a political no-man's land in 2024.

[Also read: Nikki Haley lays the foundation to seize Trump's mantle in 2024]

Pence is a traditional conservative from the establishment wing of the GOP that predominated before Trump, and many “America First” Republicans don’t trust the vice president to perpetuate his boss’ populist legacy. Meanwhile, some traditional conservatives are suspicious of Pence, skeptical of supporting him for a future presidential bid because he jettisoned long-held positions on key issues, like immigration and trade, to join up with Trump.

“His problem is that while, obviously, he’s attached to Trump as his vice president, on a policy level there will likely be other candidates who better represent the Trump ‘America First’ base,” said a Republican operative who supports the president and previously served in the administration.

“Pence is absolutely not the next GOP nominee, and frankly, it’s because of Trump,” argued a Republican operative who opposes the president and has considered backing a 2020 primary challenger should a serious contender emerge.

As 2020 approaches, Pence’s singular focus is the Republican ticket, reflecting his philosophy that the team always comes first. But the vice president and his team of experienced operatives understand that his best case for the nomination in 2024 is Trump’s re-election. That’s why Pence has been doing far more than what has been asked of him.

Since the beginning of Trump’s term, the vice president has taken the initiative, assembling a political operation that allowed him to fill the critical role of party builder on Trump's behalf that would have been assumed by a more traditional, less mercurial president. This effort, helpful to Republicans up and down the ballot, has simultaneously allowed Pence to begin building the national political network he would need to run for president. But was he has created is not strong enough to scare off challengers.

If Trump wins a second term, Pence will likely be more aggressive, and overt, about his ambitions, fully expecting that he might have to run in a crowded and competitive primary. Indeed, there are other Trump allies among the possible 2024 contenders, including Secretary of State Mike Pompeo and Sen. Tom Cotton, R-Ark. Former U.S. Ambassador to the United Nations Nikki Haley, nominally an ally of the president, also is interested in running.

“I don’t think these days there’s a coronation. I don’t think that’s the way it works anymore,” said a Republican who supports Pence.

Trump, if he chooses to play kingmaker, could change that.

But Republican insiders question whether Trump would reward Pence’s allegiance, noting that with this president, loyalty is not always a two-way street. The president’s pull with the GOP base is as strong as any Republican historically, and winning another four years would give him enormous sway over his successor for the 2024 nomination.

Should Trump pick Pence, said a Republican strategist, and “spend the first half of his second term helping” the vice president, Pence might muscle out competitors and “emerge as an heir apparent.”

[Also read: Joe Biden takes heat for calling Mike Pence a 'decent guy']