The cable news channel will require contenders to place in the top 10 in polling average.
"Proud to endorse Hillary Clinton," Vermont Gov. Peter Shumlin wrote on Twitter.
A staff shakeup is underway at Priorities USA Action.
Rick Harrison has invited the GOP White House hopeful to his home next week.
King said he expected to make a decision by the end of June.
"I'm certainly flattered by it, but I'm not holding my breath," Julian Castro said.
Fifty-seven percent voice a good or excellent opinion of GOP hopefuls, more than in 2012 or 2008.
Donald Trump says he "would build a wall like nobody can build a wall."
Lorella Praeli lived illegally in the country for 13 years.
Mark Hensch 05/20/15 11:07 AM EDT
“This administration doesn’t have a strategy,” the potential GOP presidential candidate said.