Trump says he'll release second 'very important' Ukraine call memo

* President plans to release details of second call with Zelenskiy* Mulvaney challenges inquiry’s power to summon advisers* How Trump’s hardball tactics put the constitution in perilDonald and Melania Trump on Saturday leave the White House to fly to Alabama. Trump said: ‘I will give you a second transcript, because I had two calls with the president of Ukraine.’ Photograph: Michael Reynolds/Pool/EPAAs the impeachment inquiry continued to cast dark clouds over the White H