AT&T has told employees that hiring President Trump's personal lawyer was a "big mistake." AT&T is also reportedly forcing its chief lobbyist to retire.

"Our company has been in the headlines for all the wrong reasons these last few days and our reputation has been damaged," AT&T CEO Randall Stephenson told employees in an internal memo Friday. "There is no other way to say it—AT&T hiring Michael Cohen as a political consultant was a big mistake."

The memo was published by The Washington Post. The memo said that chief lobbyist Bob Quinn is retiring, "but a person familiar with the matter said Mr. Quinn was being forced to leave," according to The Wall Street Journal.

AT&T paid $600,000 to Trump lawyer Michael Cohen's shell company, Essential Consultants, for consulting services related to AT&T's purchase of Time Warner Inc., corporate tax reform, and regulatory matters before the Federal Communications Commission. Quinn oversaw the hiring of Cohen, according to Reuters. Hiring Cohen's firm "seems to have been one of Quinn's first major decisions in the job," Talking Points Memo wrote.

Quinn became AT&T's Executive VP of External and Legislative Affairs in October 2016 and had been with AT&T since 1993, originally as a lawyer. Quinn has led AT&T's opposition to federal net neutrality rules and other regulations.

"To be clear, everything we did was done according to the law and entirely legitimate," Stephenson wrote in the internal memo to employees. "But the fact is our past association with Cohen was a serious misjudgment. In this instance, our Washington DC team's vetting process clearly failed, and I take responsibility for that."

Reuters, citing an anonymous source, reported that "AT&T's board of directors does not hold Stephenson responsible for the lack of vetting."

AT&T's External and Legislative Affairs group will now be led by General Counsel David McAfee. "David's number one priority is to ensure every one of the individuals and firms we use in the political arena are people who share our high standards and who we would be proud to have associated with AT&T," Stephenson's memo said.

Advice on Time Warner merger

Cohen provided AT&T with advice about how it "should approach the administration about its $85.4 billion merger and regulatory issues before the Federal Communications Commission," The New York Times reported on Wednesday.

An invoice that Cohen sent to AT&T was published last night by The Washington Post.

Cohen's company was charged with "creatively address[ing] political and communications related issues facing AT&T," according to the invoice's "scope of work" section.

"The broader strategic team will be expected to regularly advise on corporate interests at the Legislative and Executive (with focus on the FCC) branches of government as well as broader issues facing the AT&T brand and the telecom/tech industry in the media," the invoice says. "The position requires focus on specific long-term planning initiatives as well as the immediate issue of corporate tax reform and the acquisition of Time Warner."

AT&T paid Cohen's company $50,000 a month for 12 months, after signing a services agreement on January 23, 2017. The work was 50 percent "legislative policy development" and 50 percent "regulatory policy development," according to the invoice.

Congressional Democrats on Wednesday asked US regulators for information on whether the AT&T payments to Trump's personal lawyer were made in order to influence the government's review of the Time Warner merger. "[P]olitical influence in antitrust law enforcement is unacceptable," Senator Amy Klobuchar (D-Minn.) and Rep. David Cicilline (D-R.I.) told the Department of Justice in a letter.

AT&T's attempt to gain DOJ approval of its merger failed, as the DOJ filed a lawsuit to block the deal. AT&T could still complete the merger if it gets a favorable court ruling.