Here is what we know so far about the controversy dogging Trump's young presidency:
How did it all begin?
In October last year, US intelligence agencies publicly blamed Russia for the hacking and leak of embarrassing documents from the Democratic Party during the 2016 presidential campaign.
Three months later, on January 6, intelligence chiefs released a limited report stating they were confident that Russian President Vladimir Putin was behind an effort to damage the election chances of Trump's Democratic rival, Hillary Clinton.
The Justice Department, FBI and intelligence agencies are continuing to investigate Russia's alleged interference in the campaign.
In Congress, three Senate committees and one House committee have also opened overlapping investigations into multiple aspects of the Russia controversy.
How is Trump involved?
The various congressional inquiries are notably looking into contacts between the Trump campaign and Russian officials, both before and since the November 8 election, to determine whether there was any collusion with Russian attempts to influence the vote outcome.
Several Trump aides had longstanding business links to Russia or Moscow-backed Ukrainian politicians, including his campaign manager Paul Manafort who resigned last August under scrutiny over the issue.
The White House has vehemently denied a New York Times report that Manafort and two others from the campaign communicated with Russian intelligence officials prior to the election.
What is the fallout so far?
Revelations of sensitive contacts between the Trump team and Russia have already caused one high-profile casualty for the incoming administration.
Trump's national security adviser Michael Flynn was forced to resign February 13 after it was reported that he had talked to the Russian ambassador the same day that outgoing president Barack Obama was expelling 35 Russian diplomats in retaliation for the election meddling.
Congressional inquiries are notably looking into whether Flynn undermined the Obama administration's sanctions on Russia in his discussions with envoy Sergey Kislyak.
On Thursday, top Democrats demanded that Sessions, Trump's attorney general, resign for failing to disclose his own contacts with Kislyak while testifying in Senate confirmation hearings.
Independent probe?
As head of the Department of Justice, Sessions oversees any FBI or other investigations.
In light of the new revelations, politicians from both parties have urged him to recuse himself from probes into the Russian controversy.
Sessions responded that he would do so "whenever it's appropriate."
Democrats fear that Trump's Republicans, who hold a majority in both chambers, will seek to stifle congressional inquiries to protect the president.
Many are now calling for a major bipartisan or independent investigation into Russian interference.
Options could be a powerful independent prosecutor, a select congressional committee, or a bipartisan commission led by experts outside government.
Republicans have so far resisted going beyond the existing committee probes.
