The White House asked the U.S. Congress on Sunday to examine whether the Obama administration abused its investigative authority during the 2016 campaign, as part of an ongoing congressional probe into Russia's influence on the election.
The request came a day after President Donald Trump alleged, without supporting evidence, that then-President Obama ordered a wiretap of the phones at Trump's campaign headquarters in Trump Tower in New York.
White House spokesman Sean Spicer said Trump and administration officials would have no further comment on the issue until Congress has completed its probe, potentially heading off attempts to get Trump to explain his accusations.
"Reports concerning potentially politically motivated investigations immediately ahead of the 2016 election are very troubling," Spicer said in a statement.
Trump made the wiretapping accusation in a series of early morning tweets on Saturday amid expanding scrutiny of his campaign's ties to Russia. An Obama spokesman denied the charge, saying it was "a cardinal rule" that no White House official interfered with independent Justice Department investigations.
Under U.S. law, a federal court would have to have found probable cause that the target of the surveillance is an "agent of a foreign power" in order to approve a warrant authorizing electronic surveillance of Trump Tower.
"There was no such wiretap activity mounted against the president-elect at the time as a candidate or against his campaign," former Director of National Intelligence James Clapper, who left the office at the end of Obama's term, said on NBC's "Meet the Press."
The White House offered no evidence on Sunday to back up Trump's accusation and did not say it was true.
Spokeswoman Sarah Huckabee Sanders, appearing on ABC's "This Week," said Trump has "made very clear what he believes, and he's asking that we get down to the bottom of this. Let's get the truth here."
Democrats said Trump was trying to distract from the rising controversy about possible ties to Russia. His administration has come under pressure from Federal Bureau of Investigation and congressional investigations into contacts between some members of his campaign team and Russian officials during his campaign.
Trump, who is spending the weekend at his Florida resort, said in his tweets on Saturday that the alleged wiretapping took place in his Trump Tower office and apartment building in New York, but there was "nothing found."
Senate Democratic leader Chuck Schumer of New York said Trump had either made a false accusation, or a judge had found probable cause to authorize a wiretap.
"Either way, the president's in trouble," he said on NBC's "Meet the Press," adding that if Trump was spreading misinformation, "it shows this president doesn't know how to conduct himself."
Attorney General Jeff Sessions said last week he would stay out of any probe into alleged Russian meddling in the 2016 election after it emerged he met last year with Russia's ambassador, although he maintained he did nothing wrong by failing to disclose the meeting.
Trump's first national security adviser, Michael Flynn, resigned in February after revelations that he had discussed U.S. sanctions on Russia with the Russian ambassador before Trump took office.
Josh Earnest, the White House press secretary under President Obama, said the president did not have the authority to unilaterally order a wiretap of a U.S. citizen.
"The president was not giving marching orders to the FBI about how to conduct its investigation," he said on ABC.