8:47 a.m. ET March 5, 2017  President Trump called Sunday for a congressional investigation of his claims that predecessor Barack Obama had him wiretapped during last year's election  —  while critics accused Trump of trying to distract people from an investigation into his own relationship with Russia.

"Reports concerning potentially politically motivated investigations immediately ahead of the 2016 election are very troubling," White House spokesman Sean Spicer said in a statement a day after Trump accused Obama — without evidence — of having Trump Tower in New York wiretapped in connection with an investigation of Russia.

Trump is "requesting that as part of their investigation into Russian activity, the congressional intelligence committees exercise their oversight authority to determine whether executive branch investigative powers were abused in 2016," Spicer said.

While Trump repeatedly tweeted about Obama during the weekend, Spicer's statement said "neither the White House nor the President will comment further until such oversight is conducted."

A spokesman for Obama said Trump's claim is false, and noted that presidents do not have the legal authority to authorize wiretaps in any case.

House Democratic leader Nancy Pelosi, D-Calif., said Trump is making false claims against Obama in order to distract attention from investigations into possible contacts among Trump, his associates, and Russians involved in a plan to hack Democratic officials during last year's election.

Again calling for an outside investigation into Trump and Russia, Pelosi told CNN's State of the Union: "What do the Russians have on Donald Trump?"

Rep. Devin Nunes, R-Calif., who chairs the House Intelligence Committee, said it "will make inquiries into whether the government was conducting surveillance activities on any political party’s campaign officials or surrogates" as part of its overall probe into Russian intelligence activities. Nunes said, "we will continue to investigate this issue if the evidence warrants it.”

There is no evidence Trump or his aides were the subjects of surveillance during last year's election,

Any kind of wiretap in connection with an investigation of Russia would have to be approved by a special court acting under the Foreign Intelligence Surveillance Act. That law, passed in 1978 to reform the excesses of intelligence surveillance during the Richard Nixon administration and earlier presidencies, requires law enforcement to obtain an order from a special court of federal judges before they conduct telephone surveillance on people in the United States.

James Clapper, who was director of national intelligence last year, told NBC's Meet The Press that to his knowledge there was no FISA court order regarding Trump Tower.

Clapper also said he saw no evidence of "collusion" between the Trump campaign and Russia during the 2016 election.

Hours before the White House call for a congressional investigation, Trump continued his extraordinary and unprecedented public attack on his predecessor, tweeting about Obama's relationship with Russian President Vladimir Putin. "Who was it that secretly said to Russian President, "Tell Vladimir that after the election I'll have more flexibility?" Trump said.

Obama, who denied authorizing wiretaps on anybody and would be prevented by law from doing so in any case, did make the "flexibility" comment during a discussion with then-Russian President Dmitri Medvedev ahead of the 2012 election. It came in connection with talks over a proposed missile defense system.

The attacks on Obama come amid investigations of any contacts between Trump, his associates and Russians who may have been involved in efforts to influence last year's presidential election.

In addition to the crack at Obama, Trump criticized the investigation into the hacking of Democratic National Committee officials involved in the 2016 election. "Is it true the DNC would not allow the FBI access to check server or other equipment after learning it was hacked?" Trump said. "Can that be possible?"

During his Saturday tweet storm, Trump said of the previous president: "Terrible! Just found out that Obama had my "wires tapped" in Trump Tower just before the victory. Nothing found. This is McCarthyism!"

McCarthyism is a reference to the anti-communist crusades of Sen. Joseph McCarthy, a Wisconsin Republican who led a series of investigations about alleged communist influence in the U.S. government. He was eventually censured by the Senate in 1954 and died from alcoholism-related problems in 1957.

Trump spokeswoman Sarah Sanders, speaking on ABC's This Week, said the president believes an investigation of his predecessor's actions is warranted. "All we're saying is let's take a closer look," Sanders said. "Let's look into this."

Obama spokesman Kevin Lewis said the last administration had a "cardinal rule" that "no White House official ever interfered with any independent investigation led by the Department of Justice."

As a result, Lewis said, "neither President Obama nor any White House official ever ordered surveillance on any U.S. citizen. Any suggestion otherwise is simply false."

Trump's claims about wiretapping inspired more calls for a special prosecutor investigation of Russian involvement in last year's election,  one that would include the president and campaign associates.

The FBI and various congressional committees are already looking into the Russians' election role.

As investigations proceed and revelations mount, expect Trump to continue to make unfounded allegations about his opponents, some Democrats said. "As the Russia investigation gets closer and closer to Trump, he's going to promote more conspiracy theories, not less," said Democratic political strategist Jesse Ferguson.

Attorney General Jeff Sessions, stung by disclosures he met with the Russian ambassador to the United States last year, announced last week he would recuse himself from any investigation involving the Trump campaign in which he worked.

Trump criticized Sessions' decision, and said his critics are engaged in a "witch hunt" over Russia — a group in which he presumably includes Obama.

Certainly presidents have had disputes with each other throughout American history, from John Adams and Thomas Jefferson to Lyndon Johnson and Nixon. But the public nature of Trump's accusations against Obama may well be unprecedented.

Historian Joshua Zeitz said Trump appears to be engaged in a "somewhat calculated play" to keep his Republican base behind him, but that can be "a dangerous game."

In previous presidential rivalries, Zeitz said, "the new president was wildly more popular than the former president" and that is "not the case today. In fact, quite the opposite."