President Donald Trump avoided directly answering when asked whether he currently is or has ever worked for Russia after a published report said law enforcement officials, concerned about his behavior after he fired FBI Director James Comey in 2017, had begun investigating that possibility.
Trump said it was the "most insulting" question he'd ever been asked.
The New York Times report Friday cited unnamed former law enforcement officials and others familiar with the investigation.
Trump responded to the story Saturday during a telephone interview broadcast on Fox News Channel after host Jeanine Pirro, a personal friend, asked the Russia question.
"I think it's the most insulting thing I've ever been asked," Trump said. "I think it's the most insulting article I've ever had written, and if you read the article you'll see that they found absolutely nothing."
Trump never answered Pirro directly, but went on to assert that no president has taken a harder stance against Russia than he has.
"If you ask the folks in Russia, I've been tougher on Russia than anybody else, any other ... probably any other president, period, but certainly the last three or four presidents."
Trump's claim was disputed by Virginia Sen. Mark Warner, the top Democrat on the Senate Intelligence Committee. He said almost all the sanctions on Russia arose not in the White House but in Congress, due to concerns by members of both parties about Moscow's actions. Warner accused the White House of being very slow to put in place the penalties.
The Times reported that FBI agents and some top officials became suspicious of Trump's ties to Russia during the 2016 presidential campaign but didn't open an investigation at that time because they weren't sure how to approach such a sensitive probe.
Trump's behavior in the days around Comey's May 2017 firing helped trigger the counterintelligence part of the probe, according to the newspaper.
In the inquiry, counterintelligence investigators sought to evaluate whether Trump was a potential threat to national security. They also sought to determine whether Trump was deliberately working for Russia or had unintentionally been influenced by Moscow.
Trump tweeted early Saturday that the report showed that the FBI leadership "opened up an investigation on me, for no reason & with no proof" after he had fired Comey.
Robert Mueller took over the investigation when he was appointed special counsel soon after Comey's firing. The overall investigation is looking into Russian election interference and whether Trump's campaign coordinated with the Russians, as well as possible obstruction of justice by Trump. The Times says it's unclear whether Mueller is still pursuing the counterintelligence angle.
Sen. Chris Coons, D-Del., said the report "may well suggest what it was that helped start this investigation in the first place." He and other Democratic senators said this report and others within the past week questioning Trump's behavior toward Russia give new urgency to the need for the Mueller investigation to be allowed to run its course.
Trump's lawyer Rudy Giuliani told the Times he had no knowledge of the inquiry but said that since it was opened a year and a half ago and they hadn't heard anything, apparently "they found nothing."
Trump has also repeatedly and vociferously denied collusion with the Russians.
Warner spoke on CNN's "State of the Union" and Coons on "Fox News Sunday."