Elon Musk of Tesla and Walt Disney's Bob Iger have quit. Jeffrey Immelt of General Electric and JPMorgan Chase's Jamie Dimon have dissented.

President Donald Trump's business brain trust -- originally these executives, plus some 50 other chief executive officers chosen to help shape White House policy -- has so far come up short on big ideas.

In fact, there's been little activity for the strategy and policy forum and the manufacturing group, according to people familiar with the matter who asked not to be identified. After initial meetings early in Trump's presidency -- which the White House promoted with great fanfare -- his administration hasn't convened the groups for months or set firm dates for future meetings, according to the people.

As turmoil has engulfed Washington, some prominent business leaders, including several of these informal advisers, have begun to distance themselves from the president.