In a stunning speech, 2012 Republican presidential nominee Mitt Romney labeled Donald Trump a fake, a phony, a fraud who would make the United States poorer and less safe.
Romney also said of Trump, "His promises are as worthless as a degree from (now defunct) Trump University."
He went on to attack Trump business expertise by pointing to his failed companies, "Whatever happened to Trump Airlines, Trump University, Trump magazine, Trump vodka, Trump Steaks, Trump mortgage?"
Romney called for Republicans to support the other three GOP nominees still in the hunt - Sens. Ted Cruz, Marco Rubio and Ohio Gov. John Kasich.
It's worth noting that in 2012, Romney sought and received Donald Trump's endorsement for president.
The 2008 Republican presidential nominee, Sen. John McCain, issued a statement echoing Romney: "I share the concerns about Donald Trump that my friend and former Republican nominee Mitt Romney described in his speech."
"I would also echo the many concerns about Mr. Trump's uninformed and indeed dangerous statements on national security issues that have been raised by 65 Republican defense and foreign policy leaders," continued McCain.
UPDATE - Other GOP presidential nominees chimed in after the speech: