President Donald Trump on Wednesday called Boeing a "big disappointment" after the manufacturer pushed back when it expects its beleaguered 737 Max to return to service after two fatal crashes. "Very disappointing company," Trump told CNBC's Joe Kernen in an interview when asked about Boeing's new timeline. "This is one of the greatest companies of the world, let's say, as of a year ago and all of a sudden things happened." Boeing executives have told suppliers and airline customers that it doesn't foresee regulators lifting a flight ban on the 737 Max until June or July, months later than originally expected. The new timeline that Boeing disclosed on Tuesday after it was first reported by CNBC sent Boeing's stock down more than 3%. Boeing shares were little changed in premarket trading on Wednesday after Trump's comments. The company is under fire for including a flight-control system on the planes that was later implicated in the two crashes and not telling pilots about it before the planes were first flown commercially in 2017. Trump's comments represent a sharp shift in tone on Boeing, one of the country's largest exporters and defense contractors. Last week at a White House signing of the phase one trade deal with China, Trump urged Boeing executives to resolve the Max issues quickly.

President Donald Trump speaks with CNBC at the 2020 World Economic Forum in Davos, Switzerland on Jan. 22nd, 2020. Gerry Miller | CNBC

"Get that going. Work together," Trump had told CFO Greg Smith, Reuters reported. "We've got to get that one moving fast and it's going to be better than ever I think." Regarding new Boeing CEO Dave Calhoun, Trump said at the event last week: "It's not your fault. He just got there." Treasury Secretary Steve Mnuchin earlier this month estimated the Max problems could slow U.S. economic growth by half a percentage point. The crisis over the planes, which regulators grounded in March after two nearly new Boeing 737 Max jetliners crashed within five months, has already cost thousands of jobs. Boeing suspended production of the planes this month, a move that has rippled through its supply chain and cost airlines more than $1 billion in revenue. Boeing is scrambling to complete fixes for the planes, but regulators have said they have no set timeline for when they will allow them to fly again. The Max was Boeing's best-selling aircraft and it has a backlog of more than 4,000 of them. Boeing reiterated to CNBC this week that the manufacturer doesn't plan to lay off or furlough employees who work on the 737 Max. Earlier this month, the company said it would reassign thousands of workers to other aircraft programs and facilities. The Chicago-based company employees more than 150,000 people.

Employees work on Boeing 737 MAX airplanes at the Boeing Renton Factory in Renton, Washington on March 27, 2019. Jason Redmond | AFP | Getty Images