What exactly is Scott Brown’s role in this presidential campaign?

Donald Trump (left) shook hands with Scott Brown in February after Brown endorsed the real estate mogul ahead of New Hampshire’s presidential primary.Mike Segar/REUTERS

Former US senator Scott Brown did not hold back Monday in a Republican National Committee call with reporters intended to counter an Ohio rally featuring his one-time opponent, US Senator Elizabeth Warren, and Hillary Clinton.

Among the many lines he leveled, Brown said Warren should take a DNA test to prove her Native American heritage, which she claimed in employment applications to two law schools, including Harvard. That might have appeared off-message to some, but perhaps not: Around the same time, presumptive Republican presidential nominee Donald Trump said roughly the same thing in an interview.

This prompts the question: What exactly is Brown’s role in this presidential campaign?

Brown was one of Trump’s first and most prominent endorsements, offering his support just days before the first-in-the-nation primary in New Hampshire. But Brown doesn’t have an official role with Trump campaign -- perhaps a result of his Fox News contract. Meanwhile, even former US representative Michele Bachmann of Minnesota has been given a title.

What’s more, he hasn’t been seen running in and out of Trump Tower to huddle with its namesake like New Jersey Governor Chris Christie and Dr. Ben Carson. But Brown helped organize a Boston fund-raiser for Trump on Wednesday and sat in the first row for a speech the candidate gave last month in New Hampshire.

By day, Brown offers commentary for Fox News, calling himself a “supporter” but not a “surrogate” for Trump. At night, he rocks out with his guitar in a band. Last weekend, he helped Habitat for Humanity build a house in New Hampshire and attended an event honoring veterans. On Monday, he tweeted about a beached whale.

Brown described his role to radio host Alan Colmes last week as one of “counsel” to Trump, even on matters like Twitter.

“I told him a lot of what was happening in the debates,” Brown said to Colmes. “I suggested what were going to be the attacks, and how you should handle it. I suggested he be more disciplined, not only with the tweets, but with the comments. Focus on getting policy and focusing on being more prepared when it comes to answering the easy media gotcha questions. He’s doing better.”

So what exactly is Brown trying to achieve in this race?

Since moving to New Hampshire and losing the US Senate race there two years ago, the state’s election laws and political environment leave Brown with few options politically. US Senator Kelly Ayotte, a Republican who officiated his daughter’s wedding, is seeking reelection this year. There are open-seat races for governor and his new home’s state Senate seat, but he doesn’t meet the residency requirement to run for those roles.

That means the only place Brown can go is up -- well, at least the prospect of it. NBC News put Brown on a list of 10 people who Trump could pick as his running mate (though eight others, they argued, were more likely to get the nod). There is also possibilities for a Trump cabinet spot, such as Veterans Affairs.

But asked about it on that RNC conference call, Brown wouldn’t say whether he was being vetted to be Trump’s vice president.

“I am not going to perpetuate any stories regarding what I am doing and not doing with Mr. Trump,” Brown said.