(CNN) A weekend of bombshells deepened the most intractable mystery of Donald Trump's presidency -- one that could eventually dictate his fate -- over his deference to Vladimir Putin and behavior that often favors Russia's goals.

Stunning revelations included a disclosure that the FBI opened a probe amid fears that Trump was covertly working for Moscow and detailed his "extraordinary" efforts to hide the content of his private talks with Putin.

The reports -- from The New York Times, CNN and The Washington Post -- took intrigue about Trump and Russia to a surreal new level, even after two years of shocking developments borne out of Moscow's election meddling in 2016.

The developments continued into Monday morning when CNN reported that transcripts from closed-door congressional interviews with two FBI officials detail that the agency debated whether Trump was "following directions" of Russia.

In an interview with Fox News on Saturday evening, Trump denied he was trying to conceal details of his dealings with Putin.

"I'm not keeping anything under wraps. I couldn't care less. I mean, it's so ridiculous. These people make it up," Trump said.

And speaking to reporters Monday morning, the President flatly denied having ever worked for Russia.

"I never worked for Russia and you know that answer better than anybody. I never worked for Russia," Trump said. "Not only did I never work for Russia, I think it's a disgrace that you even asked that question because it's a whole big fat hoax. It's just a hoax."

But the deeply reported accounts beg the question why Trump, given the knowledge that he and his campaign are being investigated for links to Russia, so often acts in a manner that sharpens suspicion about his ties to Moscow.

There is also growing concern in Washington about the consequences of a situation where the Kremlin knows exactly what went on in Putin's meetings with Trump around the world, but his own top foreign policy aides do not.

The situation is bound to raise new questions about Trump's past business relationship with Russia and whether the Kremlin has information that is being used to compromise the President and may explain what often appears to be efforts to obstruct the investigation into his conduct.

If, as the White House says, Trump has no compromised relationship with Russia, why does he go out of his way to hide his interactions with Putin? Does he perhaps not trust his own team not to leak details of their meetings?

The latest reports are already exacerbating a febrile atmosphere in Washington, which is polarized over a government shutdown triggered by a dispute over Trump's border wall that is now entering its fourth week.

The possibility that House Democrats could eventually seek to impeach the President has been a reverberating presence in the capital for months, and the latest reports about Trump and Russia will hardly calm the mood.

The Putin mystery

The White House bitterly attacks the media over its coverage of Trump and Putin, most recently in a pair of statements by spokeswoman Sarah Sanders over the weekend.

But neither the President nor his aides have ever offered an adequate explanation of why so much that the President says or does -- from his praise to Putin, his denigration of US intelligence agencies over their assessments of Russian election meddling and his hostility to US allies -- often favors the Kremlin.

While there is so far no proof that Trump is under Russia's influence, such a scenario -- though stunning, given that he is the President of the United States -- would help explain why his policies so often seem to favor Moscow.

This includes his hostility to NATO, his sudden announcement of a US withdrawal from Syria that the Kremlin supports, his recent comment that the Soviet Union was justified in invading Afghanistan in 1979 and his willingness to accept Russia's version of the election meddling allegations.

Trump's warmth towards authoritarian leaders, disdain for international organizations, support for Britain's exit from the European Union and coolness towards liberal, international democracy also help further Putin's goal of discrediting the political institutions and credibility of the West.

Even the chaos and political polarization Trump has fomented in America fits Putin's desire to see the world's top democratic powers discredited and in turmoil, and may be a lasting payoff of Russia's activity in 2016.

Some observers have seen such activity in itself as a form of collusion with Russia -- a hostile power -- in plain sight, even while Trump's team is under investigation for alleged campaign transgressions.

Trump under siege

The new developments follow weeks of damaging revelations and filings surrounding special counsel Robert Mueller's investigation, which has revealed repeated links between Trump associates and Russia at a time when the Kremlin was running a 2016 intelligence operation to put Trump in office and a pattern of lying about those contacts.

How much of Mueller's report is made public is likely to rest on the shoulders of William Barr, Trump's attorney general nominee, who has drawn scrutiny for comments critical of the Mueller investigation.

Barr sought to assuage some of those concerns on Monday, writing to the Senate that he will look to "provide as much transparency as I can consistent with the law" and asserting that it will be "in the best interest of everyone ... that this matter be resolved by allowing the special counsel to complete his work."

"I can assure you that, where judgments are to be made by me, I will make those judgments based solely on the law and will let no personal, political, or other improper interests influence my decision," Barr wrote in remarks he intends to deliver at his first public confirmation hearing on Tuesday.

The President has responded to the weekend's staggering reports by going on the attack, again denying there was any "collusion" between his campaign and Russia in 2016 and reacting to the report that the FBI investigated why the President was seeming to act in ways that benefited Russia after he fired the bureau's director James Comey by alleging it is a symptom of corruption with the nation's preeminent law enforcement agency.

When asked on Fox News Saturday about the Times report , Trump said, "It's the most insulting thing I've ever been asked" and claimed that he had probably been tougher on Russia than any other previous president.

It's true that the Trump administration has taken some steps that fit into an authentically hardline policy towards Moscow. This includes sanctions against Russia for election meddling and approving the sale of lethal arms to Ukraine, a step the Obama administration did not take.

But Trump's own felicity toward Putin -- on show at the Helsinki summit last year -- often seems to undermine his own administration's policy.

In the coming days, Democrats will try to block a move by the administration to ease sanctions against Oleg Deripaska, a Russian oligarch who is close to the Russian leader and is an associate of jailed former Trump campaign chairman Paul Manafort.

Senior Democrats on Sunday painted the latest developments involving Trump and Russia as a grave turn in the investigation. They're readying a sweeping oversight effort into what happened in 2016, and Trump's personal and business relationships with Moscow.

"I think we're seeing these independent actions, even independent of Mueller, which is the lead-up and some of the rationale about why this investigation started and why so many Americans, like myself, have been concerned for so long," said Democratic Sen. Mark Warner of Virginia, on CNN's "State of the Union" on Sunday.

Warner also raised the case of Konstantin Kilimnik, a business associate of Manafort who is regarded as a Russian intelligence asset. A botched legal filing last week by Manafort's lawyers revealed that the former campaign chairman had passed proprietary campaign data to Kilimnik.

Trump's legal team has played down the issue. But the big unanswered question is whether the President was aware of Manafort's behavior or whether he was acting alone.

There have been several other revelations that undermine the idea that there was no collusion between Trump associates in Russia. They include the conversations between former national security adviser Michael Flynn and Russia's ambassador to Washington during the presidential transition. The willingness of the President's son to meet a Russian lawyer in the hope of getting "dirt" on Hillary Clinton's campaign also fanned suspicion.

Republicans shrug off latest bombshells

Republicans, publicly at least, tried to downplay the latest developments.

"There is an incredible divide between Washington and the rest of the country when it comes to Bob Mueller and the Russia investigation," Texas Sen. Ted Cruz said on NBC's "Meet the Press."

"The mainstream media, Washington, is obsessed with it. And when you get outside the Beltway, I don't find anybody concerned with this at all."

Wisconsin Republican Sen. Ron Johnson was not concerned at the implications of the Post report, which said Trump confiscated his interpreter's notes taken in his meetings with Putin and banned them from talking about what went on with other administration officials.

"This is not a traditional President. He has unorthodox means. But he is President of the United States. It's pretty much up to him in terms of who he wants to read into his conversations with world leaders. That's just the basic fact," Johnson said.

And South Carolina Sen. Lindsey Graham strongly pushed back on the report that the FBI opened an investigation into why Trump was working in ways that seemed to benefit Russia.

"I find it astonishing and to me, it tells me a lot about the people running the FBI. ... I don't trust them as far as I throw them," Graham said on "Fox News Sunday."

The solidarity of the GOP senators was a sign, that for now at least, the new intrigue has not shaken Trump's hold on the Republican base over Russia -- a foundation tended daily by conservative media pundits who rarely let up their attacks on Mueller.

But, that is not a guarantee that the political ground will not shift when Mueller delivers his final report.