Mitt Romney already has gone after Donald Trump, suggesting there might be a “bombshell” in the tax returns Trump now refuses to make public.

Romney is stepping it up a notch, giving a speech today starting at 11:30 a.m. Eastern, in which he lashes out at Donald Trump:

Mitt Romney will call Donald J. Trump “a phony” and “a fraud” in a speech on Thursday in which he will urge Republicans to rally around one of Mr. Trump’s presidential rivals, according to excerpts from his remarks.

The hastily organized speech, to be delivered in Utah, represents a last-ditch effort among leaders in the Republican Party to blunt Mr. Trump’s momentum before he runs away with the presidential nomination. Mr. Romney has been criticizing Mr. Trump on social media in recent weeks, calling on him to release his tax returns and arguing that slowness to denounce the Ku Klux Klan was disqualifying for a presidential candidate.

“Donald Trump is a phony, a fraud,” Mr. Romney will say. “His promises are as worthless as a degree from Trump University. He’s playing the American public for suckers: He gets a free ride to the White House and all we get is a lousy hat.”

The former Massachusetts governor and 2012 presidential candidate, who considered making a third run in 2016, will argue that Mr. Trump’s economic policies would create another recession and that he is not suited to represent America on the global stage.

“Donald Trump says he admires Vladimir Putin, while has called George W. Bush a liar,” Mr. Romney will say. “That is a twisted example of evil trumping good.”

Needless to say, Trump and his supporters are not taking this lying down, noting how Romney welcomed Trumps endorsement four years ago:

Bonus Question: Does this help or hurt Trump?

UPDATE:

Here’s the short version:

Here is the speech, in full: