Mr Trump startled millions of people when he claimed earlier this month - without providing details or evidence - that his predecessor had carried out electronic surveillance of Trump Tower. The White House then asked congress to investigate the claims.
Two congressional committees asked the government to provide it with any information to support the claim by Monday evening. But the Department of Justice has now revealed it has asked politicians at the two committees who will take up the claim, for more time.
Is it legal for a sitting President to be "wire tapping" a race for president prior to an election? Turned down by court earlier. A NEW LOW!— Donald J. Trump (@realDonaldTrump) March 4, 2017
A department spokeswoman said it needed more time “to review the request in compliance with the governing legal authorities and to determine what if any responsive documents may exist”.
The House Intelligence Committee responded by saying it wanted a statement by the time of a planned hearing on March 20, suggesting it would use a subpoena if that did not happen.
“If the committee does not receive a response by then, the committee will ask for this information during the March 20 hearing and may resort to a compulsory process if our questions continue to go unanswered,” said spokesman Jack Langer.
Mr Trump’s claim that Mr Obama had wiretapped him during the campaign, set off a firestorm.
Observers pointed out that any surveillance could only have been undertaken by the FBI after obtaining a warrant from a Foreign Intelligence Surveillance Act (FISA) court - implying that a judge must have believed there was sufficient suspicion of wrongdoing to grant such approval.
Intelligence officials told US media they were not aware of any such operation being carried out.
Mr Obama’s spokesman said “neither President Obama nor any White House official ever ordered surveillance on any US citizen. Any suggestion otherwise is simply false”.
Terrible! Just found out that Obama had my "wires tapped" in Trump Tower just before the victory. Nothing found. This is McCarthyism!— Donald J. Trump (@realDonaldTrump) March 4, 2017
The White House then said Mr Trump had based his claim on reports in the media - apparently something he read on the right wing Breitbart News site.
This week, the White House started to walk away from Mr Trump’s claim, saying that he had not necessarily been speaking literally when he said Mr Obama had wiretapped him.
Spokesman Sean Spicer told reporters: “He does not think Obama went out there and wiretapped him personally. There are are a whole host of techniques to or surveil someone.”
He added: “The president was very clear in his tweet that it was wiretapping - that spans a whole host of surveillance types of options. The House and the Senate intelligence committees will now look into that and provide a report back.”
Yet many pointed out that Mr Trump only referred to wiretapping in his tweet, which read: “How low has President Obama gone to tapp my phones during the very sacred election process. This is Nixon/Watergate. Bad (or sick) guy!”
Reuters said that under US. law, presidents cannot direct wiretapping. Instead, the federal government can ask a court to authorise the action, but it must provide justification.
Republicans have distanced themselves from the president over the issue. Republican Senator John McCain said over the weekend that the president should either prove the claim or retract it.
Meanwhile, Congressman Adam Schiff, the top Democrat on the House committee, has said he plans to question FBI Director James Comey over Mr Trump’s wiretapping charge.
Mr Comey has called on the Justice Department to deny the allegation, according to law enforcement sources.