Michael Cohen resigns from RNC committee post, sources say

Michael Cohen, President Trump's longtime confidant and former personal attorney, has resigned from his post as deputy finance chair of the Republican National Committee's Finance Committee, sources close to the RNC told ABC News.

In his resignation letter to Ronna McDaniel, the RNC chair, Cohen cited the ongoing special counsel investigation as one reason for his departure. ABC News has reviewed the email.

"This important role requires the full time attention and dedication of each member. Given the ongoing Mueller and SDNY investigations, that simply is impossible for me to do," he wrote.

Cohen also criticized the administration's policy of separating migrant children from their parents at the southern border, the first time he's distanced himself from the president.

"As the son of a Polish holocaust survivor, the images and sounds of this family separation policy is heart wrenching," Cohen wrote. "While I strongly support measures that will secure our porous borders, children should never be used as bargaining chips."

Cohen on Tuesday hired New York lawyer Guy Petrillo to represent him in a federal investigation headed up by the Southern District of New York.