McGahn played a role in Trump's selection of both Kavanaugh and Justice Neil Gorsuch as candidates for the Supreme Court.
Don McGahn has been the Washington-savvy lawyer by Donald Trump's side since the start of his presidential bid back in July 2015.
President Donald Trump's White House legal counsel, Don McGahn, may leave the administration in short order after cooperating extensively with Special Counsel Robert Mueller's investigation into possible criminal wrongdoing from Trump.
He was not aware that Trump planned to send the tweet before it posted, according to a person close to McGahn. Trump said that that story was "fake news."
But Mr McGahn was well-liked in Washington DC, with Senate Judiciary Chair Chuck Grassley lamenting his departure.
Some GOP lawmakers sounded stunned at McGahn's departure. McGahn's exit also continues the churn of staffers as the administration sets records for turnover and the White House struggles to fill key vacancies.
"Don's significance to the judiciary, the White House and the nation can not be overstated, and I look forward to his continued efforts on behalf of our country", McConnell added.
McGahn and many high-level White House officials were caught off guard by Trump's tweet, which followed a report by Axios earlier in the day that McGahn was preparing to leave.
"People like him", Ms Sanders said of Mr Flood.
The White House lawyer reportedly threatened to resign past year because Mr Trump was planning to remove Mr Mueller. "But there's not a plan locked in place at this point". Other topics included Trump's comments regarding Attorney General Jeff Sessions, a frequent target of critical tweets from the president, and the possibility of firing Deputy Attorney General Rod Rosenstein, who oversees the probe, the Post said.
Sessions has been repeatedly belittled by the President and the Justice Department chief told the White House he might have to leave his job if Trump fired Deputy Attorney-General Rod Rosenstein, who oversees the Russian Federation investigation, according to people familiar with the exchange.
As White House counsel, McGahn was charged with untangling a thicket of conflicts of interest between Trump's global business interests and his presidency.
"He was surprised", the source said.
The departing chief White House lawyer was the top attorney on Trump's 2016 campaign.