Two senior senators asked the FBI and Justice Department on Wednesday, March 8 for any information they have on President Donald Trump's unsubstantiated claim that his predecessor Barack Obama wiretapped him during the 2016 U.S. presidential campaign, Reuters reports.

In a letter to James Comey, director of the Federal Bureau of Investigation, and Acting Deputy Attorney General Dana Boente, Republican Lindsey Graham and Democrat Sheldon Whitehouse wrote:

"We request that the Department of Justice provide us copies of any warrant applications and court orders ... related to wiretaps of President Trump, the Trump campaign, or Trump Tower.”

Under U.S. law, presidents cannot direct wiretapping. Instead, the federal government can ask a court to authorize the action, but it must provide justification.

Asked at a briefing on Wednesday if Trump was the subject of a probe, White House spokesman Sean Spicer replied: "There is no reason that we have to think that the president is the target of any investigation whatsoever."

Dianne Feinstein, a Democratic member of both the Senate intelligence and judiciary committees, told CNN she had not seen any evidence that Obama had tapped Trump's phone.

"It's all rather shocking to me that a sitting president would make this kind of an allegation about a former president without any proof whatsover," she said. "I believe it's patently false."