U.S. President Donald Trump says Russian officials "must be laughing" at the United States with its escalating investigations into Moscow's meddling in last year's election, which he asserts was "a lame excuse" by opposition Democrats to explain losing the White House.
In a Twitter comment Tuesday, Trump said accounts of the probes of links between Trump campaign aides and Russian operatives aimed at helping him win have "taken over the Fake News," his derisive term for U.S. media.
Later, at a White House briefing for reporters, spokesman Sean Spicer said Trump "is frustrated ... to see stories come out that are patently false, to see narratives that are wrong, to see, quote, unquote, fake news, when you see stories get perpetrated that are absolutely false, that are not based in fact.
"That is troubling," Spicer added, "and he is rightly concerned."
Former U.S. Secretary of State Hillary Clinton, who lost to Trump, has partly blamed Russian interference in the election for her defeat.
WATCH: Clinton on her election loss, Russian interference
But Trump has been dismissive of the investigations, even as his own Justice Department appointed a special counsel to probe whether his campaign aides colluded illegally with Russia, and several congressional panels have embarked on their own fact finding.
ABC News reported that congressional investigators had asked one of Trump's closest confidants, his personal attorney, Michael Cohen, to tell them about contacts he has had with people connected to the Russian government, but he said he turned down the invitation. Cohen told the television network the request was "poorly phrased, overly broad and not capable of being answered.”
Kushner's back-channel communications
Trump's Russia comment came as news reports continued to focus on Jared Kushner, Trump's son-in-law and a White House adviser, and his reported attempt to establish a back-channel communications link to Russian officials in the weeks before Trump's inauguration in January.
Spicer deflected several questions about Kushner's actions, telling one reporter his inquiry "presupposes facts that have not been confirmed."
The White House is also bracing for the upcoming congressional testimony of former FBI chief James Comey. Trump fired Comey after allegedly asking him to drop the probe into former national security adviser Michael Flynn and his close ties to the Kremlin.
U.S. Senator John McCain, a key foreign affairs figure in Congress, said he views Russia and its president, Vladimir Putin, as the "greatest challenge we have," even more so than that posed by Islamic State terrorists.
Speaking during a visit to Australia, McCain told the Australian Broadcasting Company Russia has tried to "destroy the very fundamental of democracy" with efforts to influence the U.S. presidential election and others elsewhere in the world.
MCain voiced concerned about the Kushner effort to establish the secret link to Russia.
"I know that some administration officials are saying, 'Well, that's standard procedure,'" McCain said Monday. "I don't think it is standard procedure prior to the inauguration of a president of the United States by someone who is not in an appointed position."
The White House says Kushner "was acting in his capacity as a transition official," and that he has agreed to discuss the meetings with congressional investigators.
Trump has rejected allegations his campaign colluded with Russia.
"Jared is doing a great job for the country," Trump told The New York Times late Sunday. "I have total confidence in him. He is respected by virtually everyone and is working on programs that will save our country billions of dollars. In addition to that, and perhaps more importantly, he is a very good person."
The 36-year-old Kushner, a New York real estate executive before joining Trump's White House staff, is married to Trump's oldest daughter Ivanka, who is also a White House adviser.
According to several news accounts, Kushner sought to create the secret communications link with Moscow as he met with the Kremlin's ambassador to the United States, Sergey Kislyak, last December.
Some foreign affairs experts said the move, while former President Barack Obama had weeks left in his term, worried them that it could undermine U.S. security, and some opposition Democrats have suggested Kushner's security clearance should be revoked. Other experts say exploring the creation of "back channels" is commonplace, even during presidential transitions.
Trump's Tuesday attack on the U.S. news media, a near constant during his campaign and the first four months of his presidency, was his second in three days.
On Sunday, he wrote on Twitter, "It is my opinion that many of the leaks coming out of the White House are fabricated lies made up by the #FakeNews media. Whenever you see the words 'sources say' in the fake news media, and they don't mention names, it is very possible that those sources don't exist, but are made up by fake news writers. #FakeNews is the enemy!"
He later added a defense of his use of Twitter, saying the media "works hard at disparaging & demeaning my use of social media because they don't want America to hear the real story!"
VOA's Chris Hannas contributed to this report.