'Worst possible nightmare': Former US attorney says Trump should be sweating bullets over Cohen's new plea deal

Former Trump "fixer" Michael Cohen's surprise new plea deal with special counsel Robert Mueller sent shock waves through Washington on Thursday -- and one former U.S. Attorney thinks it signals major trouble for President Donald Trump.

Talking with ABC News, former U.S. Attorney Kendall Coffey says that Cohen's deep knowledge of Trump's business activities should terrify the president in terms of what he could provide to investigators.

“The potential significance of Cohen’s cooperation is immense," he said. "But for most high-powered business people with complex business interests, having one’s personal attorney become a star witness for the prosecution is the worst possible legal nightmare."

Although Coffey couldn't say for certain that Cohen's plea deal will lead to criminal charges against Trump and his associates, he did say that Cohen's "cooperation has already created the most serious federal allegations to date concerning President Trump, and more may be coming."

Cohen on Thursday pleaded guilty to making false statements to Congress about the Trump Tower Moscow project. As part of the plea deal, Cohen also gave Mueller's office over 70 hours of testimony.

Earlier this year, Cohen pleaded guilty to making illegal hush money payments to adult film star Stormy Daniels and Playboy model Karen McDougal “at the direction” of Trump, who was described in the plea as a candidate for federal office.

Cohen also admitted in his plea that he made the illegal payment “for the purpose of influencing” the 2016 presidential election by covering up the president’s “alleged affairs.”