HARTFORD (AP) — As Connecticut Gov. Dannel P. Malloy makes political pitches for presidential candidate Hillary Clinton and fellow Democratic governors on the campaign trail, the chairman of the Democratic Governors Association faces challenges back home, including a federal criminal investigation into fundraising for his 2014 re-election campaign and low public approval numbers.

It remains unclear, however, whether those challenges will make Malloy a less appealing surrogate as the election season heats up even more.

Malloy appeared Tuesday night on MSNBC's "Hardball with Chris Matthews" and lashed out at Republican Donald Trump for declaring gun rights supporters might still find a way to stop Clinton from naming anti-gun Supreme Court justices, comments that some interpreted as openly encouraging violence against Clinton.

"It's this bravado, this sick bravado of Donald Trump, where he's just tougher than everybody else and because he's so much tougher than anybody else he can just put anything out there and somebody will clean up the mess after him," Malloy said.

Earlier that same day, Malloy was asked by reporters in Connecticut about the federal probe into whether the Connecticut Democratic Party illegally spent about $278,000 in political contributions from contractors that were earmarked for federal government candidates to pay for a mailing benefiting Malloy's successful re-election campaign. The party contends the mailers touting Malloy's record were part of a "get-out-the-vote" effort that helped federal candidates as well. The mailers included a phone number to get a ride to the polls and polling hours.

Malloy appeared reluctant to talk about Connecticut U.S. Attorney's Office convening a grand jury to investigate the matter. Federal investigators appear to have been interested in the mailers shortly before the November 2014 election, according to emails released last week. They were first obtained by The Connecticut Post and Hartford Courant.

"I'm not going to be pulled into an ongoing regular discussion on this stuff," said Malloy, a former prosecutor who noted how he shouldn't be commenting on a grand jury investigation. "I think people have a right to take a look. They're taking a look. We'll see where it goes. It's the party, and we'll see where it ends."

Malloy signed an affidavit in 2014 agreeing he would not supplement the $6.5 million in public funds he received from the Citizens Election Fund for his campaign. Campaign staff also signed documents agreeing to abide by the program's rules.

National Republicans have criticized Malloy about the criminal investigation and his flagging popularity. A Quinnipiac University Poll in June showed 24 percent of state voters approve of the job he's doing as governor.

After Malloy's speech before the Democratic National Convention last month, the Republican Governors Association claimed the governor "conveniently failed to mention that he is facing numerous scandals in Connecticut, where his governorship has been a disaster." The probe was later raised with Malloy during a July 31 interview on Fox News, where Maria Bartiromo asked whether he misappropriated funds while running for re-election.

Malloy described the investigation as "an election examination of fundraising and expenditures" and that he's "quite confident that it will be resolved."

A message was left seeking comment with the Clinton campaign about whether it's concerned about using Malloy as a surrogate.

Connecticut Senate Minority Leader Len Fasano, R-North Haven, first raised the issue in 2014 about the Democratic mailers with the State Republican Party, which challenged their use to the State Elections Enforcement Commission. The Democrats later agreed to make a $325,000 payment to the state to settle the complaint. The party has said it complied with all federal and state laws.

Fasano predicted it will be difficult for Malloy to distance himself from the federal probe.

"It's his campaign committee that's being investigated, along with the state party and I don't think you can separate Governor Malloy from either the two," Fasano said. "It's pretty common knowledge that Governor Malloy was in charge of the state party in 2014 and his guys were running the re-election of his campaign."

Quinnipiac University Poll Director Doug Schwartz said Malloy's challenges will unlikely be noticed outside Connecticut

"People don't really know outside of Connecticut that's he's unpopular," he said. "If he does a good job supporting the party's nominee, that's what will matter to the Clinton campaign."