Mitt Romney just ripped Donald Trump's 'hurtful' comments and predicted they'll cast a 'shadow' over the race

Former Massachusetts Gov. Mitt Romney (R) ratcheted up his criticism of real-estate magnate Donald Trump in a new interview released Friday.

Romney, the Republican 2012 presidential nominee, discussed Trump during a wide-ranging interview with David Axelrod, who as President Barack Obama's top campaign adviser helped defeat Romney three years ago.

"I think Donald Trump has said a number of things which are hurtful - and he has said that they were 'childish' in some respects - and I think [they] will be potentially problematic either in the primary or a general election," Romney said.

"And they relate to things he's said about women, and things he's said about members of the news media, things he's said about Hispanics," he added. "I think he'll have some challenges if he proceeds to the next stage."

As a Republican presidential candidate in 2012, Romney went out of his way to secure Trump's endorsement. But as Trump has risen to become the Republican 2016 front-runner, Romney has let it be known that he shares the GOP's establishment's disdain for Trump's candidacy. 

Last month, Romney predicted that Trump won't win the Republican nomination because the business mogul isn't a "mainstream conservative ... who has a foundation in foreign policy that gives people confidence that they can guide the ship of state in troubled waters."

Speaking with Axelrod, Romney further predicted that Trump's heated remarks about illegal immigration could create obstacles for whomever their party nominates next year. Trump frequently accuses the Mexican government of sending "rapists" and other criminals across the US border.

"Donald Trump has a big megaphone, and I think that some of the things he's said, particularly about Hispanics, will be problematic - certainly for him if he were to go to the next stage - but for whoever our nominee is," Romney said.

However, Romney suggested that former Florida Gov. Jeb Bush (R), who has a Mexican-American wife and speaks Spanish, and Sen. Marco Rubio (R-Florida), a Cuban-American also fluent in Spanish, could deflect those concerns among Hispanic voters in the general election.

"Now, if our nominee happened to be someone like Marco Rubio or Jeb Bush, who have strong Hispanic roots themselves and connections themselves, that might not be as big an issue. But if it were someone else who didn't have those connections, why, it could probably remain as a shadow over their campaign," he said.

For his part, Trump frequently blasts Romney on Twitter for losing the election to Obama.