WASHINGTON — White House press secretary Sean Spicer said Thursday that President Trump “stands by” his allegation that former president Barack Obama ordered wiretapping surveillance of Trump Tower last fall, despite statements from the leaders of congressional investigations that no evidence had been found to support the claim.

In a remarkably combative exchange with reporters at his daily press briefing, Spicer was asked whether Trump still believes Obama ordered the alleged surveillance effort.

“He stands by it,” Spicer said, going on to assail journalists for the way they have reported on the controversy.

Earlier Thursday, the Republican and Democratic leaders of the Senate Intelligence Committee said their investigation into the matter so far has turned up no evidence that the U.S. government had conducted surveillance on Trump Tower in New York, either before or after the election on Nov. 8, 2016.

“Based on the information available to us, we see no indications that Trump Tower was the subject of surveillance by any element of the United States government either before or after Election Day 2016,” read the statement by Sen. Richard Burr, R-N.C., the committee chairman, and Virginia Sen. Mark Warner, the committee’s ranking Democrat.

In a Fox News Channel interview on Wednesday, Trump acknowledged that he based his initial accusation on news reports that referenced wiretapping generally. He said that information would soon be revealed that could prove him right.

“I think you’re going to find some very interesting items coming to the forefront over the next two weeks,” Trump told Fox host Tucker Carlson.