WASHINGTON (Reuters) - In a heated moment during his unconventional and combative news conference on Thursday, President Donald Trump’s command of the facts was openly challenged by a reporter who asked, “Why should Americans trust you?”

The issue was the margin of victory in the U.S. Electoral College, which Trump asserted early in the news conference was the “biggest” since fellow Republican Ronald Reagan, who was elected in 1980 and 1984.

Trump defeated Hillary Clinton by a 304-227 tally of state-by-state electors, who represent votes cast in the election. Seven electors voted for someone else.

“We got 306 because people came out and voted like they’ve never seen before so that’s the way it goes,” the president said.

Twitter exploded with fact-checking of Trump’s statement.

Although proportionally he had 306 electoral votes on the night of the Nov. 8 election, two of those electors defected when they cast official ballots on Dec. 19.

A quick check by a reporter at the news conference showed President Barack Obama, a Democrat, amassed more electoral votes in 2008 (365) and 2012 (332). In 1988, President George H.W. Bush, a Republican, drew 426 electoral votes.

Few observers, however, were expecting a White House reporter to confront Trump about it in real time, while sitting in the East Room. Within minutes the reporter, Peter Alexander of NBC News, stood and corrected Trump, noting Obama’s and Bush’s tallies and asking whether Americans could trust the president to state the facts.

“Why should Americans trust you when you accuse the information they’ve received of being fake when you’re providing information that’s not accurate?” the TV correspondent asked.

Trump seemed to blame his staff. “I was given that information,” he replied. “Actually, I’ve seen that information around.” Trump then called on another reporter.

On the 2016 campaign trail and since taking office on Jan. 20, Trump has made criticizing the media a centerpiece of his communications strategy. Trump turned the tables later in the news conference, complaining again about coverage of his young administration.

“I want to see an honest press,” Trump said. “The public doesn’t believe you people anymore.”