WASHINGTON — When Donald Trump took the oath of office on Jan. 20, he became the first president to move into the White House while under official investigation into whether he had ties to a foreign adversary.

As Trump was sworn in, the FBI and the Senate Intelligence Committee had already begun digging to find out if Trump or his campaign had coordinated with Russia to defeat his Democratic rival, Hillary Clinton.

And in his first 100 days as president, a cloud of suspicion has hung over Washington, sustained by Trump’s praise of Russian President Vladimir Putin, his staff’s ties to Russia and a steady drip of news stories and leaks.

“It’s not only something new about the first 100 days, but it is of a character that is more explosive,” said Bruce Miroff, a presidential historian at the University at Albany. “It’s hard to put this in an historical frame because it is unprecedented.”

Trump and his aides deny they worked with Russia on the election. Trump has dismissed the allegations as “fake news” and “a political witch hunt.” And Trump accused President Barack Obama and his officials of leaking classified documents and conducting surveillance of his team.

But Democrats and some Republicans have insisted on a thorough probe of links between Trump’s campaign and Russia, as part of the larger review of Russian hacking, trolling and attempts to interfere in the 2016 presidential election.

advertisement | advertise on newsday

Though no smoking gun has turned up so far, Rep. Adam Schiff (D-Calif.), top Democrat on the House intelligence panel, said last week that “it’s premature” to determine an outcome. “I do think we need to get to the bottom of these allegations of collusion or coordination,” he said.

Trump’s first 100 days has been filled with surprising twists and turns arising from the Russian meddling in the campaign, including the hacking of Democratic servers and posting thousands of internal emails, according to the FBI, CIA and NSA.

In mid-February, Trump fired his national security director, retired Gen. Michael Flynn, for misleading Vice President Mike Pence about bringing up U.S. sanctions on Russia for meddling in the U.S. election in phone calls with Russian diplomat Sergey Kislyak.

In January, acting U.S. Attorney Sally Yates had warned the White House counsel that Flynn could be vulnerable to Russian blackmail because his failure to disclose that he mentioned sanctions to Kislyak. Trump fired Yates soon after for defying him on his travel ban order.

Two weeks after Flynn was fired, Attorney General Jeff Sessions recused himself from the Russia probe after a news story revealed he met twice — including once in his office — with Kislyak but failed to disclose it when questioned during his Senate confirmation hearing.

In a March 4 tweet storm, Trump made accusations: “Terrible! Just found out that Obama had my ‘wires tapped’ in Trump Tower just before the victory. Nothing found. This is McCarthyism!” Obama denied it. The FBI and NSA said they have not found evidence of it.

James Clapper, Obama’s director of national intelligence, appeared the next day on NBC’s “Meet the Press” and denied Trump’s wiretap claim. Asked about Trump ties to Russia, he said that as of when he left his post, “we had no evidence of such collusion.”

But FBI Director James Comey revealed on March 20 that the FBI last July had opened a counterintelligence investigation of Russian interference in the 2016 election and “any links between individuals associated with the Trump campaign and the Russian government.”

Meanwhile, the news media has reported on at least a dozen Trump campaign and other associates who have ties to or met with Russians — from Trump business partner Felix Sater to Trump’s adviser and son-in-law Jared Kushner, who met with Kislyak.

They include Paul Manafort, Trump’s campaign manager for six months, who worked with a pro-Russian Ukrainian politician; Roger Stone, a Trump friend who tweeted notice of WikiLeaks’ release of Democratic emails before they were posted; and businessman Carter Page, who reports say was wiretapped by the FBI on suspicion Russians were trying to recruit him. All three issued denials of complicity with the Russians.

advertisement | advertise on newsday

But the House and Senate intelligence committees have struggled with differing levels of partisan division, and their slow pace has emboldened other congressional committees to step up and conduct their own probes.

The House intelligence panel’s investigation ran off the rails, several lawmakers said, resulting in the recusal of its chairman, Rep. Devin Nunes (R-Calif.), a Trump transition team member, after complaints he might have disclosed classified information in a news conference.

Nunes told reporters that sources at the White House had shown him documents in which Obama officials “unmasked,” or identified, Trump aides in foreign surveillance, and then he rushed to the White House to tell Trump. Democrats dispute his interpretation of the documents.

The House intelligence investigation, now chaired by Rep. Mike Conaway (R-Texas), will question Comey and NSA Director Mike Rogers in secret on Tuesday, and have invited Yates, Clapper and former CIA Director John Brennan to testify in public.

But after Nunes canceled an earlier planned open hearing for their testimony, Yates and Clapper will appear first before a Senate judiciary subcommittee hearing May 8.

advertisement | advertise on newsday

Meanwhile, the House Oversight and Government Reform Committee on Thursday revealed that Flynn did not fill out the proper forms or get the required Defense Department permission to accept foreign payments from Russia and Turkey.

That prompted the Defense inspector general to say it will investigate Flynn’s compliance with regulations.

And at the prodding of Democrats, even the GAO will review the Trump transition.

Amid those probes, Trump has pushed ahead with his agenda.

“When there is a scandal like this it has a tendency to absorb a lot of attention,” said Sen. John McCain (R-Ariz.). “There is always another shoe, there’s always another story, and that does over time impact the ability for us and the president to govern.”

Yet McCain said Trump’s constituents are more interested in the economy and jobs, and Miroff said the scandal tends to get lost among all the other Trump controversies.

A Quinnipiac poll found Americans are divided evenly along partisan lines on whether they believe Trump’s team coordinated with Russia. But the April 20 poll also found two thirds or more said they are concerned about Russian meddling in the election and Trump’s relations with Russia.

Miroff said the investigations’ outcome could range from finding nothing to criminal charges or even treason. In the end, he said, “They could conclude the evidence is inconclusive.”

Rep. Peter King (R-Seaford), a member of the House Intelligence Committee, said he believes there is no evidence of collusion.

“If it turns after all this there is nothing there, then it will lead people to think Trump has gotten a bad deal,” King said. “If there is something there, then it’s a whole different story.”