At a news conference hosted by Republican presidential candidate Donald Trump, Al Baldasaro, a military veteran, New Hampshire lawmaker and ardent Trump defender, lambasted members of the media for asking questions about the money Trump claims to have raised for veterans' groups. (Reuters)

The Secret Service is investigating one of Donald Trump's most outspoken supporters, a New Hampshire state representative who said this week that Hillary Clinton should be shot for treason.

“The U.S. Secret Service is aware of this matter and will conduct the appropriate investigation," Nicole Mainor, a spokeswoman for the Secret Service, said about the comments from Al Baldasaro. The investigation was first reported by the Daily Beast.

Baldasaro, a Republican from Londonderry, N.H., is a former Marine who calls himself Trump's "veteran advisor." Trump gave him a key role during a crucial moment in this campaign: In May, when Trump criticized the news media for its coverage of his promise to give $1 million to veterans groups, Baldasaro was given a speaking role and a place in the background when Trump spoke.

This week, as Republicans at the party convention in Cleveland called for Clinton to be jailed, Baldasaro went further.

“Hillary Clinton should be put in the firing line and shot for treason,” Baldasaro said earlier in the week on "The Kuhner Report," a conservative radio show hosted by Jeff Kuhner.

On Wednesday, Baldasaro stood by those comments in an interview with WMUR of Manchester, N.H. He said the death penalty was appropriate for Clinton’s handling of government emails. “As far as I’m concerned, it is treason and the penalty for treason is the firing squad — or maybe it’s the electric chair now,” Baldasaro said.

Baldasaro did not immediately respond to an email sent seeking comment on Wednesday afternoon.

Hope Hicks, a spokeswoman for the Trump campaign, said in a brief statement that "Mr. Trump and the campaign do not agree" that Clinton should be executed for treason. Hicks did not respond to a question asking whether Trump would cut ties with Baldasaro.

On Wednesday evening, Clinton's campaign was already using Baldasaro's remarks to raise money, telling supporters in an email, "One of Trump's advisors just said 'Hillary Clinton should be put in the firing line and shot for treason.' We. Are. Better. Than. This. If you agree, chip in $1..."