Ratcheting up his attacks on predecessor Barack Obama, President Trump called Sunday for a congressional investigation into whether "executive branch investigative powers were abused" by his predecessor during last year's election.

"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 him wiretapped in connection with an investigation of Russia.

Democrats said Trump is trying to divert attention from existing investigations involving the president, campaign associations, and Russian attempts to influence the 2016 election.

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."

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?"

Hours before the White House statement, Trump tweeted about his predecessor'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.

Trump, without evidence, accuses Obama of wiretapping him; 'Simply false,' Obama spokesman says

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!"

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, Wilson 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 an outside investigation of Russian involvement in last year's election.

Citing Trump's tweets about Obama, Pelosi said "the Deflector-in-Chief is at it again," and "an investigation by an independent commission is the only answer."

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