AT&T Inc. Chief Executive Officer Randall Stephenson said he was flabbergasted by the Justice Department’s suit to block his company’s takeover of Time Warner Inc., in part because he’d been a strong and public backer of the Trump administration.

Stephenson said he has been one of President Donald Trump’s “biggest defenders on public policy.” The antitrust case against AT&T’s $85.4 billion deal is “a big curve ball,” the CEO said at a forum at the Economic Club of New York Wednesday.

The telecommunications giant, the biggest provider of pay-TV service in the U.S., wants to use programming from Time Warner, the owner of HBO and the Warner Bros. studio, to sell advertising based on its data on what viewers are watching. The Justice Department argues the deal would give AT&T too much power to withhold popular programming from competitors.

But Senator Brian Schatz, a Hawaii Democrat, and other critics have questioned whether the lawsuit is motivated by Trump’s antipathy toward CNN, another network owned by Time Warner.

Stephenson, 57, has been burned before by pursuing big mergers. In 2011, AT&T abandoned the acquisition of rival wireless carrier T-Mobile US Inc. after the Justice Department sued to block the deal.

The CEO, who has led AT&T for 10 years, had plenty of praise for Trump and Republicans in Congress, saying a “rationalized” regulatory environment is simplifying decision-making for businesses and that proposed changes to the tax code would make companies more competitive internationally.

But when he learned about the Justice Department’s lawsuit, his reaction was: “Wow, what was that?”