Congressman Seth Moulton signaled Wednesday that he’s not taking lightly the president's refusal to concede his election loss.

“I think we all should be concerned,” Moulton said in an interview on Boston Public Radio. The former Marine Corps officer warned that the delayed transition between administrations is leaving the U.S. and its global allies vulnerable. He cited conclusions drawn in the 9/11 Commission Report that the delayed presidential transition in 2000 was a key factor in why intelligence pertaining to the September 11 attacks went ignored.

“This is serious stuff,” he said, adding that it’s “sad" to be having the conversation on Veterans Day, "when we should be simply talking about the amazing heroes,” American troops.

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"Instead, we have to talk about what this draft-dodging commander-in-chief might to do threaten our national security, just because he can’t accept the results of losing an election,” Moulton said.

Moulton also spoke to several worst-case scenarios, including the possibility that Trump could leak military secrets to foreign powers to ease his massive financial debts or even deploy military troops to U.S. cities to quell protests, should he refuse to leave office.

Congressional Democrats and some senior military leaders raised the latter concern after Trump fired his secretary of defense, Mark Esper, in a tweet Monday. The president had reportedly been frustrated with Esper for refusing to deploy troops to U.S. cities to quell Black Lives Matter protests in June.

And though Moulton declined to share his personal views more specifically, the Democratic congressman said, "frankly, we've got to be concerned about everything on the table. ... Every time we’ve predicted he might do something bad, he does something worse.”

“This is who this man is,” Moulton said. "He has no baseline respect for our troops. He has proven time and again as our commander-in-chief that he pays utter disregard for our national security — at least whenever his reputation is on the line. And he’s proven in the last few days that he’s going to go out kicking and screaming like a toddler when it comes to a peaceful transition of power."