The New York Times: Trump, Offering No Evidence, Says Obama Tapped His Phones. By Michael D. Shear and Michael S. Schmidt, March 4, 2017.

“It would have been difficult for federal agents, working within the law, to obtain a wiretap order to target Mr. Trump’s phone conversations. It would have meant that the Justice Department had gathered sufficient evidence to convince a federal judge that there was probable cause to believe Mr. Trump had committed a serious crime or was an agent of a foreign power, depending on whether it was a criminal investigation or a foreign intelligence one.

Former officials pointed to longstanding laws and procedures intended to ensure that presidents cannot wiretap a rival for political purposes.

“A cardinal rule of the Obama administration was that no White House official ever interfered with any independent investigation led by the Department of Justice,“ said Kevin Lewis, a spokesman for Mr. Obama. “As part of that practice, neither President Obama nor any White House official ever ordered surveillance on any U.S. citizen.“

Mr. Trump asserted just the opposite in a series of five Twitter messages beginning just minutes before sunrise in Florida, where the president is spending the weekend.

[…]

Ben Rhodes, a former top national security aide to Mr. Obama, said in a Twitter message directed at Mr. Trump on Saturday that “no president can order a wiretap“ and added, “Those restrictions were put in place to protect citizens from people like you.“ “