Former President Donald Trump could cause "angst" for North Dakota Governor Doug Burgum by choosing him as his potential running mate in this year's presidential election, former Republican Governor Ed Schafer warned on Sunday.

Burgum has emerged as a frontrunner to be Trump's vice presidential running mate, as speculation continues over who the former president will pick. Speculation about Burgum has been driven by reports about the pair forming a close personal friendship, with the governor appearing frequently on the campaign trail for him.

Burgum initially ran against Trump for the 2024 presidential nomination, but soon dropped out and endorsed him. The two-term governor is a conservative business owner and could be seen as a safe choice for Trump, offering a balance similar to that provided by Mike Pence to Trump's ticket in 2016.

He is also one of America's richest politicians, having once sold a software company to Microsoft for more than $1 billion.

In a series of posts on X, formerly Twitter, on Sunday senior political columnist at Politico Jonathan Martin wrote about an interview he had with Burgum and other Republicans about the ongoing speculation that the North Dakota governor may be Trump's running mate.

"I spent a couple hours w Burgum, a few days in the Dakotas and wrote about a very real prospect: Trump II could be shaped by a group of normie Great Plains Republicans," Martin wrote.

Martin also interviewed Schafer, who was governor of North Dakota from 1992 to 2000. According to the columnist, Schafer said Trump could cause "angst" for Burgum, adding that him being tied to Trump doesn't give a "good start."

"Knowing Trump a little and Doug well, that could cause some angst in Doug from time to time," the former governor said.

In a separate X post, Martin wrote: "Schafer, whose father used his fortune from founding Mr. Bubble to first restore Medora in the 1960s, worried out loud that Burgum being 'tied at the hip to Donald Trump doesn't give you a good start in 2028.'"

In addition, Schafer seemingly took aim at Burgum and said if he is "doing this to be president, he's better in the cabinet," adding that if he were to be vice president Burgum would have to be "a mini Donald Trump."

Newsweek has reached out to Burgum's office via email for comment.

Meanwhile, Burgum explicitly said on Fox News last week he'd be happy to serve under Trump if he's elected for a second term.

"I've got no concerns at all about being in this administration," he said. "I endorsed President Trump early in 2016, I endorsed him in 2020, and I was one of the first ones to endorse him this year. And at least in our state it's been a world of difference with President Trump in office versus President Biden."

Burgum announced in January he would not be seeking another term as North Dakota governor, boosting speculation he was interested in the vice presidency.

However, some experts have already said that nominating Burgum could be a mistake, and that Trump should select a female running mate instead.

According to Mark Shanahan, who teaches American politics at the University of Surrey in the United Kingdom, suggested that Trump will choose a vice-presidential pick who won't "outshine him."

"Trump's VP pick will be all about Trump," he previously told Newsweek. "[Mike] Pence was the perfect veep for Trump right up to January 6, 2021. He stole none of the limelight and took many of the bullets for the 45th president. He was relatively competent and never a threat."

He added: "Trump has a long history of surrounding himself with sycophants and underlings. There would be nothing worse for him than picking a running mate who could potentially outshine him."

Trump, the presumptive Republican presidential nominee, has indicated that he will announce his running mate at the Republican National Convention, which kicks off on July 15.

Meanwhile, Burgum has repeatedly deflected questions about whether he will become Trump's running mate.

"I know there's a ton of interest in this process that's going on right now about the VP thing, but I think what's clear is President Trump, who's winning across every demographic, can win this whole thing on himself," he told Fox News' Sean Hannity on June 19.