WASHINGTON – President Donald Trump on Friday extended the mystery of why Vice President Mike Pence abruptly canceled a trip to New Hampshire on Tuesday.

"There was a very interesting problem that they had in New Hampshire," Trump told reporters, without saying what the problem was.

Trump said the reason will become known "in about a week or two."

"I can’t tell you about it. But it had nothing to do with the White House," Trump said. "There was a problem up there."

Pence had been scheduled to visit a drug addiction treatment center in Salem, New Hampshire, and talk about the opioid crisis Tuesday.

As the news media awaited his arrival, a representative from Pence's office announced there had been "an emergency callback."

Pence's spokeswoman, Alyssa Farah, disputed that characterization on twitter. But added only that "something came up" that required Pence to stay in Washington.

The cancellation prompted much speculation about the cause.

Pence's top aide, Marc Short, told reporters Tuesday that the change of plans was not caused by a national security problem, a health concern or a personal or family issue.