Priorities USA, a super-PAC aligned with Hillary Clinton, has issued a dozen separate email blasts or advertisements attacking Rubio by name in the last two weeks. No other GOP presidential candidate is receiving that kind of scrutiny.

The group has taken swipes at Rubio’s use of a Republican Party credit card and his record in the Florida Legislature. Headlines have included “What Is Marco Rubio Hiding?”, “Rubio Tax Plan Debate Claims ‘Nonsense’ ” and “Rubio’s evasiveness and apparent misstatements.”

It’s a shift for the super-PAC, which in previous months seemed to be focused more on Rubio’s onetime mentor, former Florida Gov. Jeb Bush…

A Democratic strategist close to the campaign said the attacks suggest that Clinton and her allies see Rubio as likely to win the nomination, given Bush’s problems, and that they believe the party will pick an establishment figure over an “outsider” candidate such as businessman Donald Trump, retired neurosurgeon Ben Carson or Texas Sen. Ted Cruz.