Trump impeachment inquiry awaits key witnesses, but some will be no-shows

US President Donald Trump speaks to the media on the South Lawn of the White House in Washington upon his return from New York, U.S. [Reuters]

US lawmakers leading an impeachment inquiry of President Donald Trump have scheduled another crucial round of testimony this week, but several key White House witnesses plan to defy them and some other administration officials could follow suit.

Refusals by Trump loyalists to appear before Democratic-led committees could set the stage for a battle between the White House and lawmakers over their power to conduct the investigations. Some Democrats say Trump, who has ordered administration officials not to cooperate, should face an obstruction of justice charge among the impeachment counts they plan to consider against him.