Devin Nunes, the chairman of the House Intelligence Committee, had sought to turn the investigation away from Russia and toward President Donald Trump's allegations that the previous Obama administration had abused its powers by spying on Trump and his advisors.
Rancor over Nunes's sharing top secret intelligence reports with Trump -- but not members of his own committee -- had driven the committee's probe to a halt.
Nunes said he was stepping aside "temporarily" for another committee Republican, Mike Conaway, to lead the probe while he fights House ethics charges that he leaked classified information.
"The charges are entirely false and politically motivated, and are being leveled just as the American people are beginning to learn the truth about the improper unmasking of the identities of US citizens and other abuses of power," he said in a statement.
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Probe under a political cloud
Nunes's actions had cast a cloud over the investigation into Russian interference in last year's presidential campaign and whether any Trump aides or associates collaborated with Moscow.
In January, US intelligence chiefs said Russian President Vladimir Putin had masterminded the hacking and disinformation campaign that aimed to damage Trump election rival Hillary Clinton and tip the vote in favor of the real estate magnate.
Trump has repeatedly called that charge "fake news." Instead, he has demanded an investigation into whether Obama staff combed top secret intelligence intercepts to dig up damaging information on his team.
"The real story turns out to be SURVEILLANCE and LEAKING! Find the leakers," he tweeted on Sunday.
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Nunes drew criticism after he went to the White House on March 21 to view top secret files he said indicated abuse of intelligence by the Obama administration.
The files were intelligence intercepts of the communications of foreign officials, which were either with US officials or mentioned their names. Under US privacy laws, the names of Americans in such intercept files have to be masked.
But Nunes said publicly he had discovered files where the names had been unmasked by unnamed Obama officials, and he took his discovery to Trump, while not sharing it with his committee.
Democrats accused Nunes of seeking to protect Trump while ignoring the core Russia allegations.
Watch: Nunes says he wants to speak to ethics committee as soon as possible to clear his name
Getting 'back on track'
Nunes's stepping aside came after weeks of public tensions between himself and Adam Schiff, the Democratic vice chairman of the Intelligence Committee.
Schiff said Thursday that it would allow the Russia probe to get "fully back on track."
"The important work of investigating the Russian involvement in our election never subsided, but we have a fresh opportunity to move forward in the unified and nonpartisan way that an investigation of this seriousness demands," he said.
Paul Ryan, the Republican Speaker of the House, said Nunes's problems had become a "distraction" for the committee.
"I am confident (Conaway) will oversee a professional investigation into Russia's actions and follow the facts wherever they lead," Ryan said.
The House panel is one of several bodies examining the Russia scandal.
The Federal Bureau of Investigation has been investigating the issue since June, when it became clear to US intelligence that the Russian government was behind hacks of Democratic Party communications and a misinformation campaign.
In Congress, the Senate intelligence committee is also proceeding with its own investigation.
Last week, the committee said it wanted to interview at least 20 people in private. The list is believed to include members of Trump's presidential campaign and top intelligence officials.
Abuse of intelligence intercepts?
But Nunes's revelations about the intercepts have boosted Trump's claims that Obama officials had misused intelligence powers to spy on his operations before and after the election.
On Tuesday, Obama's national security adviser Susan Rice acknowledged reports that she had unmasked some of the Americans in the intercepts.
Rice said her actions were legal as part of an intensified look into how Russia had interfered in the election.
"The allegation is that somehow Obama administration officials utilized intelligence for political purposes. That's absolutely false," she told MSNBC television.
