TRUMP: Romney was begging so much, I could've said, 'Mitt, drop to your knees...'

GOP frontrunner responded to former Mitt Romney's critical speech on Thursday by saying the candidate "begged" for his endorsement.

"He was begging for my endorsement," Trump said at a rally later in the day in Portland, Maine.

"I could've said 'Mitt, drop to your knees.' He was begging me," he added.

Trump was referring to the 2012 race for president in which Romney, the GOP nominee, sought Trump's endorsement.

More to come from Trump's Thursday speech.