Manafort changing legal strategy as Mueller probe expands

— -- As part of former Trump campaign chairman Paul Manafort changing his legal defense team, sources close to the one-time Trump adviser tell ABC News that this change in legal counsel signals a bigger change in strategy as Manafort prepares for a lengthy fight that has nothing to do with Russia collusion and election interference.

It was just last month that federal authorities executed a search warrant at a home in Virginia belonging to Manafort. Sources told ABC News that the search warrant, issued by the FBI, stems from the ongoing investigation by special counsel Robert Mueller into Russia's meddling in the 2016 presidential election and possible collusion between the Trump campaign and the Russian government.

According to a source familiar with the investigation, Manafort was awoken by a group of armed FBI agents knocking on his bedroom door as they executed the warrant on July 26.

Sources close to Manafort say he has already provided Congress with extensive documents in response to the requests from multiple committees. The sources add that it was part of those disclosures to Congress where Manafort revealed the June 2016 meeting between Donald Trump Jr., Jared Kushner and a Russian attorney at Trump Tower, first reported by the New York Times.

The sources add it is unclear how much more Manafort will cooperate with the Congressional investigation given the expanding focus of the Mueller probe.

The change in legal counsel was announced by Manafort late Thursday. A spokesperson told ABC News, "Mr. Manafort is in the process of retaining his former counsel, Miller & Chevalier, to represent him in the office of special counsel investigation. As of today, WilmerHale no longer represents Mr. Manafort."

Manafort joined the Trump campaign during the 2016 primaries and ran the Republican National Convention. He resigned from the campaign in late August 2016 once reports surfaced about his work abroad.

Just last month, Manafort registered as a foreign agent for past work on behalf of Ukraine, his spokesperson confirmed at the time to ABC News.

As the investigation on Capitol Hill continues, ABC News has recently reported that the Trump campaign sent more than 20,000 pages of documents to a Congressional committee on Aug. 2, the deadline to submit documents to the committee.

Manafort produced about 400 pages, including his foreign agent advocacy paperwork. In letters to Manafort and Trump Jr., the Senate Judiciary Committee asked for all documents related to their June 2016 meeting with Russian lawyers, as well as any communications with or records of attempts to obtain information from Russians about Hillary Clinton or the 2016 presidential campaign.