(BLOOMBERG)- The top Democrat on the House Intelligence Committee said President Donald Trump's former national security adviser would have to go through several steps before lawmakers would consider offering immunity in exchange for his testimony.

Representative Adam Schiff of Washington said that he would discuss Mike Flynn's offer with the Senate Intelligence Committee and the Justice Department, and that he would need to receive details about what Flynn would say.

"As with any investigation - and particularly one that grows in severity and magnitude by the day - there is still much work and many more witnesses and documents to obtain before any immunity request from any witness can be considered," Schiff said Friday (March 31) in a statement.

Trump encouraged Flynn to seek immunity from prosecution Friday morning, calling investigations into alleged contacts between the Trump administration and the Russian government a political "witch hunt." "Mike Flynn should ask for immunity in that this is a witch hunt (excuse for big election loss), by media & Dems, of historic proportion!" Trump wrote in a Twitter post, using shorthand for Democrats.

While it's unclear if Trump was coordinating with his former adviser, Flynn has told investigators that he's willing to be interviewed in return for immunity from prosecution.

"General Flynn certainly has a story to tell, and he very much wants to tell it, should the circumstances permit," Robert Kelner, a lawyer for Flynn, said in a statement late Thursday.

"We will not comment right now on the details of discussions between counsel for General Flynn and the House and Senate Intelligence Committees, other than to confirm that those discussions have taken place."

Jack Langer, a spokesman for the House Intelligence Committee, said that the panel "had a preliminary conversation with Michael Flynn's lawyer about arranging for Flynn to speak to the committee. The discussions didn't include immunity or other possible conditions for his appearance."

Flynn Wants Immunity

Here's why it's complicated: White House Press Secretary Sean Spicer said Friday that Schiff is expected to visit the White House later in the day to view intelligence intercepts.

The administration says they raise questions about whether government spy agencies improperly identified Trump's campaign officials and associates in the course of routine foreign surveillance.

The White House invited Schiff and the leaders of the Senate Intelligence Committee to view the documents shortly after the New York Times reported that two White House officials had provided House Intelligence Chairman Devin Nunes with reports showing that Trump and his associates were named incidentally by U.S. spy agencies monitoring foreign officials.

Schiff said Thursday that he would be willing to review the material, but questioned the administration's motives, saying officials may be trying to disseminate information that helps Trump's case.

The administration has been deflecting questions about Russian meddling in the presidential election by focusing on leaks of classified materials and, more recently, Trump's allegations that his predecessor may have spied on him and his aides before and after the election. Flynn's immunity offer has refocused some attention on the original questions about Russian meddling in the election.

'Highly Politicized'

Flynn's lawyer suggested immunity is justified because his client is "the target of unsubstantiated public demands by Members of Congress and other political critics that he be criminally investigated."

Kelner, a partner at Covington and Burling LLP in Washington, said, "No reasonable person, who has the benefit of advice from counsel, would submit to questioning in such a highly politicized, witch hunt environment without assurances against unfair prosecution."

Flynn, a retired lieutenant general, was forced out of the Trump administration after it was revealed that he had misled Vice President Mike Pence about his contacts with the Russian ambassador to the US after Trump's victory.

FBI Director James Comey has told Congress that the bureau's probe into Russian hacking of last year's presidential election "includes investigating the nature of any links between individuals associated with the Trump campaign and the Russian government and whether there was any coordination between the campaign and Russia's efforts."

'Mucking Around'

While Trump continued to scoff at concerns over the investigations into Russian hacking, one of his cabinet members said it's a real concern for the US and allies.

US Defence Secretary James Mattis said Friday at a London news conference with his UK counterpart that Russia "is choosing to be a strategic competitor." Its violations of international law are a matter of record, including its Crimea annexation and "mucking around" in other countries' elections, he said.

The House and Senate Intelligence committees are also investigating allegations of Russian interference in the 2016 US election, including any contacts between Trump associates and Russia.

Clinton critic Flynn, who ran the Defense Intelligence Agency under President Barack Obama, was one of Trump's closest advisers during the campaign and was one of the more vocal critics of Democratic presidential nominee Hillary Clinton, even leading chants of "lock her up" during his Republican National Convention speech regarding her use of a private email server.

"I mean, five people around her have had, have been given immunity," Flynn said in an interview with NBC's "Meet the Press" in September. "When you are given immunity, that means that you have probably committed a crime."

Flynn briefly held one of the most sensitive jobs in the Trump administration as national security adviser, which carries the highest-level security clearance. He has been at the top of the list for Democrats and others investigating the possible Russia connections.

In the weeks after Flynn left the administration, new details emerged about his business ties with Turkey's government and Russian entities.

Turkey and Russia Flynn retroactively registered as a foreign agent with the Justice Department for work that his firm, Flynn Intel Group, did for a Dutch consulting company, Inovo BV, which has ties to President Recep Erdogan of Turkey. Flynn's filing showed that his company received $530,000 from Inovo between Sept 9 and Nov 14.

Kelner wrote in a letter accompanying the filing that Flynn had previously registered with Congress under the Lobbying Disclosure Act, but made the new filing because the work could have been interpreted as benefiting the government of Turkey. Lobbying on behalf of a foreign government requires registration with the Justice Department.

The top Democrat and Republican on the House Oversight Committee are seeking documents related to Flynn's security clearance applications and contacts and payments from Russian, Turkish and any other foreign sources including the Kremlin-backed media outlet RT, dating from Flynn's 2014 retirement from the Defense Intelligence Agency to the present.

Democrats on the House committee last week released documents showing Flynn received more than $45,000 from RT for taking part in a December 2015 gala where he sat at President Vladimir Putin's table.

Other documents showed that Flynn, who received $11,250 for a 2015 speaking engagement in Washington for Kaspersky Government Security Solutions, Inc, a US subsidiary of a Russian cybersecurity firm; and an $11,250 payment from Volga-Dnepr Airlines.

Price Floyd, a spokesman for Flynn, said the retired lieutenant general "both informed and fully briefed" the Defence Intelligence Agency about his Russia trip beforehand and when he returned.