WASHINGTON — The top two senators overseeing the intelligence community joined on Thursday the chorus of lawmakers debunking President Trump’s claim that President Barack Obama wiretapped his phones last year, issuing a bipartisan statement that they had seen no evidence supporting the accusation.
“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,” said Senator Richard M. Burr, Republican of North Carolina, and Senator Mark Warner, Democrat of Virginia.
The blunt statement by the leaders of the Senate Intelligence Committee means that all four congressional leaders who oversee intelligence-based surveillance by the government have rejected Mr. Trump’s claim. On Wednesday, their counterparts on the House Intelligence Committee, Representatives Devin Nunes, a Republican, and Adam B. Schiff, a Democrat, made similar statements; both are from California.
Later on Thursday, in a set of testy exchanges with reporters, the White House press secretary, Sean Spicer, said Mr. Trump still “stands by it,” while arguing, as he has in recent days, that Mr. Trump meant wiretapping in a broad sense, that there had been some kind of surveillance-related activities.
“The bottom line is the investigation by the House and the Senate has not been provided all the information,” Mr. Spicer added.
Mr. Trump made his claim in a series of Twitter postings on March 4, announcing that he had “just found out” about the wiretapping by Mr. Obama, whom he called “a bad (or sick) guy” whose purported campaign surveillance was comparable to Watergate.
But the president offered no evidence for his claims, and suspicion quickly emerged that he had based it on a theory — circulating in some conservative circles — that Mr. Obama had conspired to sabotage Mr. Trump using government surveillance.
As days passed without evidence emerging to back Mr. Trump’s assertion, his administration first asked Congress to investigate his allegation, then refused to comment on it, and then tried to redefine what he said to have been merely a reference to some kind of general surveillance activity by investigators last year.
Mr. Trump made similar comments on Wednesday evening in an interview on Fox News, when the host, Tucker Carlson, pressed him about why he had made his statements without offering evidence. Mr. Carlson suggested that the president was devaluing his own words.
Mr. Trump said the word wiretapping “covers surveillance and many other things.” He also said that his administration “will be submitting things before the committee very soon that hasn’t been submitted as of yet — but it’s potentially a very serious situation.”
In the same interview, Mr. Trump cited news reports that he said supported his claim, including a Fox News segment on March 3 that discussed months-old reports that there had been a Trump-related surveillance order in October; reporters from The New York Times have been unable to corroborate the existence of such an order.
Mr. Trump also brought up a January article in The Times about surveillance data being used in an investigation into possible links between his aides and Russian officials.
“I’ve been reading about things,” Mr. Trump said. “I think it was a Jan. 20 article in The New York Times — they were talking about wiretapping.”
That Times article, however, did not discuss Mr. Obama ordering the wiretapping of Trump Tower. Nor did it say whether the intercepted conversations in question were the result of surveillance targeting Mr. Trump’s aides, as opposed to surveillance that targeted Russian officials but incidentally picked up conversations with Mr. Trump’s aides.