1014 GMT February 25, 2020
An Obama spokesman declared the assertion "simply false."
In a series of angry morning tweets, Trump suggested his predecessor was behind a politically motivated plot to upend his campaign. He compared the alleged events to "Nixon/Watergate" and "McCarthyism!" He called Obama a "Bad (or sick) guy," AP reported.
Trump's claims drew bipartisan rebukes from Democrats and Republicans alike who find his habit of venting on social media to be beneath the office of the president.
Trump said Saturday morning he had "just found out" the information, though it was unclear whether he was referring to a briefing, a conversation or a media report. The president has in the past tweeted about unsubstantiated and provocative reports he reads on blogs or conservative websites.
Still, the morning tweets stand out, even for the perpetually piqued Trump, given the gravity of the charge and the strikingly personal attack on the former president. Trump spoke as recently as last month about how much he likes Obama and how much they get along, despite their differences.
"How low has President Obama gone to tapp my phones during the very sacred election process. This is Nixon/Watergate. Bad (or sick) guy!" he tweeted, misspelling 'tap.'
Obama spokesman Kevin Lewis said a "cardinal rule" of the Obama administration was that no White House official ever interfered in Justice Department investigations, which are supposed to be conducted free of political influence.
"As part of that practice, neither President Obama nor any White House official ever ordered surveillance on any US citizen," Lewis said, adding that "any suggestion otherwise is simply false."
Sen. Ben Sasse, R-Neb., called on Trump to explain what he knows about the wiretapping allegations "ideally to the full public, and at a bare minimum to the US Senate."
In his morning tweets, Trump said the wiretapping occurred in October at Trump Tower, the New York skyscraper where he ran his campaign and transition. He also maintains a residence there.
The president's allegations may be related to anonymously sourced reports in British media and blogs, and on conservative-leaning US websites, including Breitbart News. Those reports claimed that US officials had obtained a warrant under the Foreign Intelligence Surveillance Act to review contacts between computers at a Russian bank and Trump's New York headquarters.