David Jackson

USA TODAY

WASHINGTON — Hours before FBI Director James Comey confirmed that his agency is investigating possible connections between the Donald Trump campaign and Russia during last year's election, the president denounced the accusations as the product of sour grapes from losing Democrats.

"(Former national intelligence director) James Clapper and others stated that there is no evidence Potus colluded with Russia," Trump tweeted Monday morning before the House Intelligence Committee began its hearing. "This story is FAKE NEWS and everyone knows it!"

The president added during an early morning series of tweets: "The Democrats made up and pushed the Russian story as an excuse for running a terrible campaign. Big advantage in Electoral College & lost!"

California Rep. Adam Schiff, the top Democrat on the House Intelligence Committee, responded to Trump just hours before using the hearing to lay out aspects of the ongoing investigation into whether Trump or campaign associates had contacts with Russians involved in hacking Democratic Party officials close to presidential nominee Hillary Clinton.

"Mr. President, the Russians hacked our election and interfered," Schiff saiid. "No one disputes this now, but you. This is what is called 'fact.'"

In his tweetstorm, Schiff also responded by citing another aspect of Monday's hearing: Trump's so-far-unfounded claims that predecessor Barack Obama had him wiretapped in the runup to the election.

"As you will see during our hearing, Mr. President, there is no evidence Mr. Obama tapped your phones," Schiff said.

Hours later, Comey confirmed there is no evidence backing Trump's wiretapping claim, a comment that came shortly after he disclosed that the president's campaign is involved in the Russia investigation.

“I can promise you we will follow the facts wherever they lead," Comey said,

Comey, who privately encouraged Justice Department officials to refute Trump's accusations soon after he made them in a March 4 tweetstorm, testified before the House Intelligence Committee along with National Security Agency Director Mike Rogers.

Democrats pounced on Comey's testimony.

“The Department of Justice and Trump administration must allow Director Comey’s investigation to move forward without any interference, meddling, or political pressure of any kind whatsoever," said Senate Democratic leader Chuck Schumer. “The possibility of coordination between the Trump campaign and Russian officials is a serious, serious matter."

Trump, meanwhile, has complained about news leaks and said that is what the committee should be looking into. "The real story that Congress, the FBI and all others should be looking into is the leaking of Classified information," Trump tweeted. "Must find leaker now!"

The wiretapping charges brought furious denials from Obama aides — who pointed out that the law forbids presidents from ordering wiretaps — and a diplomatic flap with the United Kingdom, which protested claims by Trump allies that British allies may have been involved in the wiretapping.

Despite a rising number of officials who say there is no evidence, Trump and aides have not backed down from the Obama wiretapping claim. They have often sought to buttress their case by citing news reports, many of them based on anonymous sources.

During a Friday news conference with German Chancellor Angela Merkel — whose phones had been tapped by the Obama administration — Trump told his guest: "As far as wiretapping, I guess by this past administration, at least we have something in common, perhaps."

The accusation also triggered the diplomatic row with another ally, as Trump and aides cited a report by Fox News commentator Andrew Napolitano that Obama asked a British intelligence agency to tap Trump. The British government objected and the Trump administration pledged not to use the claim again. Asked about the flap, Trump said: "That was a statement made by a very talented lawyer on Fox, and so you shouldn't be talking to me, you should be talking to Fox. OK?"

Schiff cited the diplomatic fallout in his series of tweets, including one that said: "Your suggestion British wiretapped you & jape with Merkel are harming our relationships with key allies. This is called 'collateral damage.'"