WASHINGTON - US Senator Elizabeth Warren, a progressive Democrat who has exchanged stinging criticism with President Donald Trump, said on Monday she has formed an exploratory committee to run for president in 2020. Warren, of Massachusetts, released a video in which she outlines her vision of a path to opportunity for all Americans, not just the wealthy. 'That's the America I'm fighting for. And that's why today I'm launching an exploratory committee for president,' she said.