Trump rages against Mueller in early morning rant: 'There were no charges to bring!'
President Donald Trump during an interview on Fox Business. (Screenshot/YouTube)

President Donald Trump started off the day with an angry tweet against special counsel Robert Mueller -- a day after he delivered his first public remarks in two years.

Mueller resigned as special counsel and summarized his findings Wednesday during a surprise news conference, where he said his office was prohibited from charging the president under Department of Justice guidelines and made clear his investigation had not exonerated the president.

Trump reacted shortly afterward by proclaiming his innocence, and he ranted again Thursday morning against the investigation, which Mueller seemed to indicate should be followed up by a congressional inquiry.

"The Greatest Presidential Harassment in history," Trump tweeted. "After spending $40,000,000 over two dark years, with unlimited access, people, resources and cooperation, highly conflicted Robert Mueller would have brought charges, if he had ANYTHING, but there were no charges to bring!"