Former advisor to the US president and US publicist Steve Bannon poses during a photo session in Paris on May 27, 2019.

Former chief White House chief strategist Steve Bannon quietly brought in Washington D.C. super lawyer Cleta Mitchell to represent his nonprofit, Citizens of the American Republic, CNBC has learned.

Mitchell, a partner at Foley & Lardner LLP, confirmed in an email that she is the legal counsel for the organization after she was asked for its 990 tax return, which would show detailed financial information, including how much donors contributed to the group and revenue totals.

All nonprofits are required to submit these documents through their attorneys to the Internal Revenue Service and, according to Mitchell, Bannon's organization has filed for an extension on its 501(c)(4). She did not recall the extension's deadline, and declined to comment further on how she's been helping Bannon's team.

Bannon's decision to draft Mitchell comes as he continues to protect the identity of his contributors and works to stay in the good graces of President Donald Trump. He departed the White House in 2017 under a cloud. Nonprofits are not legally required to disclose the names of their financial supporters.

Mitchell's political views are similar to Bannon's and these groups often look for legal representatives who can relate to their causes. Among other conservative groups, she represented the National Rifle Association.

Bannon, a nationalist firebrand, told CNBC in August when he first launched the group that his donors are the "savviest investors in the country." He added that they were mainly business executives who have hawkish views on China. Bannon, a China hawk himself, did not provide a single name of anyone who wrote checks for the organization.

Citizens of the American Republic website features Bannon at a fundraising event for We Build the Wall Inc., a nonprofit that supports Trump's plan to beef up security at the southern border. Bannon and former Kansas Secretary of State Kris Kobach are members of its board.

Other clips on the website feature takes on economic nationalism, fighting China and stopping illegal immigration.

Bannon did not return a request for comment.

In the past, Mitchell has been openly skeptical of former Special Counsel Robert Mueller's investigation into the Trump campaign's potential collusion with Russian operatives during the 2016 election. In an op-ed published in the National Review the same month Bannon announced his new project, Mitchell questioned why Mueller wasn't focusing on Hillary Clinton potentially breaking campaign finance laws.

"Maybe this means that Mueller might step out of his snipe hunt of an investigation of Russian 'collusion' in 2016 to take an actual interest in whether there was compliance with federal campaign-finance law by both 2016 presidential campaigns, not just President Trump's," she wrote at the time.

She was included on a list of witnesses Democrats wanted to interview when they were in the minority on the House Intelligence Committee. The Democrats on the committee wanted Mitchell to describe her work with the National Rifle Association when it was one of her clients.

Mitchell "may be able to clarify for the Committee any Russian-related approaches to and interaction with the organization [NRA] and persons of interest to the Committee during the 2016 election," Democrats on the committee wrote in 2018.

A spokesman for the now Democratic majority of the House Intel Committee declined to comment.