Democrats erupted in outrage Friday over news that Donald Trump's Justice Department secretly surveilled lawmakers probing possible collusion with Russia, reaping the phone records of top political foes in what they called an unprecedented abuse of power. 

Democrats Adam Schiff and Eric Swalwell said they were recently told by Apple that during 2017-2021 the company had been ordered to hand over records of their phone communications, as well as those of family members including a child, as Trump fought a flow of damaging leaks on his 2016 election campaign's links to Russia.

No proof they were the sources of leaks was ever presented, yet the probe stayed alive for as long as Trump remained in office, to January 2021.

Schiff called it "the weaponization of law enforcement by a corrupt president."

Senate leaders threatened to subpoena two Trump attorneys general, Jeff Sessions and Bill Barr, who oversaw the surveillance, to testify on the issue.

"This is a gross abuse of power and an assault on the separation of powers," said Majority Leader Chuck Schumer and Senate Judiciary Committee Chair Dick Durbin in a statement.

The Justice Department said Friday that its inspector general would investigate the use of subpoenas and other powers to probe lawmakers and journalists under Trump.

The secret surveillance took place as Trump faced investigations by special counsel Robert Mueller and by the House Intelligence Committee -- where Schiff was then the top Democrat -- into whether his campaign colluded with Russian election meddling and whether Trump tried to obstruct those investigations.

As they progressed and the threat of impeachment intensified, Trump accused Schiff and other Democrats of leaking classified intelligence to reporters.