Who is Devin Nunes and why is his role probing Donald Trump's Russia links controversial?

For a man who doesn't like the spotlight, the chairman of the House intelligence committee has secured himself a place in it.

Devin Nunes, a Republican congressman from the farmlands of central California, is dominating international headlines thanks to his high-profile role in one of the congressional investigations that have embroiled Donald Trump's White House. 

Last month, he held back-to-back news conferences to discuss typically secret information about US spy agencies intercepting communications of people on Mr Trump's team.

A week ago he made headlines again by admitting he went to the White House grounds to review intelligence reports and meet the secret source behind his claim that communications involving Trump associates were caught up in "incidental" surveillance.

On Thursday April 6 Mr Nunes said he would temporarily step aside from Russia probe after accusations were filed against him by left-wing activist groups with the office of congressional ethics.

Mr Nunes said the charges were false and politically motivated, but it was in the best interest of the committee to have GOP congressman Mike Conaway of Texas temporarily take charge of the committee's investigation.

Trump claims Obama wire-tapped Trump tower

The saga into alleged surveillance on Mr Trump  began on March 4 when  the president said on Twitter he "just found out that Obama had my 'wires tapped' in Trump Tower just before the victory."

Mr Trump called Mr Obama "sick" and suggested he should be criminally prosecuted for "wiretapping" him during the election campaign.

He offered no proof and it was believed he may have based them on media reports.

Sean Spicer, the White House press secretary, escalated the controversy when he suggested GCHQ may have helped Mr Obama spy on Mr Trump. Repeating a claim initially made by an analyst on Fox News, he said: "He’s able to get it and there’s no American fingerprints on it."

GCHQ called the claim "utterly ridiculous". 

Who is Devin Nunes?

Mr Nunes is chairman of the House of Representatives Intelligence Committee, which is investigating Russia's interference in the 2016 election and possible ties between the Kremlin and the Trump campaign.  It's a potentially sprawling enterprise that spans continents and plumbs spycraft.

A harsh critic of the Obama administration on issues like Benghazi, he went on to become a member of Mr Trump's transition team after the election and was reportedly instrumental in the selection of Gen. James Mattis for the role of Defence Secretary. 

In the past he has criticised those who would limit the scope of National Security Agency programs. 

"The intelligence committee - that's a committee that I call the tip of the spear, because without national security it's tough to keep those trade routes open," Nunes said in a 2014 interview with the Tulare Advance-Register.

Donald Trump and the Russian connections

Until now, much of Nunes' intelligence committee work has been focused on investigations into NSA leaker Edward Snowden, the Iran nuclear deal, Hillary Clinton's emails and the placement of a Defence Department intelligence center.

He has pledged to lead an impartial inquiry into Russia’s interference in the 2016 US election. But he has also been accused of using his position as chair of the intelligence committee in ways that seem aligned with the interests of the White House.

In February, the White House enlisted him to push back on a news article it didn't like about Trump associates' ties to Russia. The congressman has said he did nothing improper when he reached out to a reporter.

Nunes reveals surveillance of Trump

With his independence already under the microscope, Mr Nunes's actions in March have raised more questions about his ability to lead a credible investigation.

Mr Nunes told reporters that a secret source showed him intelligence reports that prove communications of the president's transition team were swept up in legal US surveillance activity.

They were not the targets of surveillance and were part of an "incidental collection".  Mr Nunes said the intercepted communications were not related to an ongoing FBI investigation into suggestions of contacts between Trump associates and Russia.

Trump wiretapping timeline

The information was brought to him through "proper channels".

"There seems to me to be some level of surveillance activity, perhaps legal, but I don’t know that it’s right," Mr Nunes said. He added that he wasn't sure "the American people would be comfortable with what I read."

After Nunes spoke to reporters on Capitol Hill, he went to the White House to tell Mr Trump and spoke to reporters again.

Trump's reaction to Nunes comments

The president was quick to seize on the remarks, saying he felt vindicated in his claims that he was wiretapped by his predecessor Barack Obama.

Asked if he felt vindicated by the revelation Mr Trump said: "I somewhat do. I must tell you I somewhat do. I very much appreciated the fact that they found what they found."

He also retweeted stories about Mr Nunes's remarks.

Nunes met source at White House

The disclosures by Mr Nunes, together with Mr Trump's response, raised suspicions that it was an effort coordinated with the White House to back up Mr Trump's assertions of wire-tapping.

Mr Nunes fuelled those fears further last week when he admitted visiting the White House the night before making the revelations.

Mr Nunes told CNN last week that he went to the White House grounds because the intelligence information was not available to Congress. He said he did not meet with Mr Trump or his aides at that time and did not coordinate the release of information with the Trump administration.

Mr Nunes spokesman Jack Langer said Mr Nunes "met with his source at the White House grounds in order to have proximity to a secure location where he could view the information provided by the source."

Democrats have said Mr Nunes can no longer run a credible investigation of Russian hacking, the US election and any potential involvement by Trump associates.

House Democratic leader Nancy Pelosi and Adam Schiff, the top Democrat on the House Intelligence Committee, have urged Mr Nunes to recuse himself from the Russia probe.

Tensions on the committee

The House investigation has been plagued with partisan divisions under Mr Nunes' leadership. After being told of the 'incidental' surveillance, Mr Nunes bypassed Democrats and went directly to the press and the White House. He later apologised to them for not informing them first, two Democrats on the committee told the New York Times.

"It was a judgment call on my part," Mr Nunes told reporters. "Sometimes you make the right decision, sometimes you make the wrong decision."

That mistrust deepened when the committee's top Democrat suggested its Republican chairman cancelled a public hearing after pressure from the White House.

Mr Nunes said he had to cancel a hearing in March with officials from Mr Obama's administration in order to have a classified briefing with the directors of the National Security Agency and Federal Bureau of Investigation.

Mr Schiff said the cancellation was not in the public interest.

"I think that there must have been a very strong pushback from the White House about the nature of Monday's hearing. It's hard for me to come to any other conclusion about why an agreed upon hearing would be suddenly cancelled," Mr Schiff told a separate news conference.

Adding to the tensions, the chairman did not tell the top Democrat on the committee about the meeting at the White House complex. It is highly unusual for a committee chairman and ranking member not to coordinate meetings related to an investigation.

Calls for independent commission

Democrats have called for an independent inquiry, similar to the commission formed after 9/11, to investigate whether there was interference in the election, who was behind it and how it could be prevented in the future. Democrat Eric Swalwell has introduced legislation to form such a body, which would comprise 12 former senior national security, law enforcement and election officials who are respected by both parties.

So far, Republicans, who control the House and Senate, have dismissed such calls, saying the intelligence committees can handle it. 

Nunes steps aside

On Thursday April 6 Mr Nunes said he would temporarily step aside from the House intelligence committee's probe into Russian meddling in the election.

In a statement he said several left-wing activist groups have filed accusations against him with the office of congressional ethics.

Mr Nunes said the charges were false and politically motivated, but it was in the best interest of the committee to have GOP congressman Mike Conaway of Texas temporarily take charge of the committee's investigation.

He said he would continue fulfilling other duties with the committee and wants to talk to the ethics committee as soon as possible to defend himself.