Trump, who in 2012 praised the then-secretary of state as "terrific,"
said at a rally here that although Clinton is "crooked" and has "bad judgment" he believes she is "qualified" to be president. But Trump said Thursday he is now changing his tune after Vermont Sen. Bernie Sanders argued earlier this month that Clinton is not qualified
, though he later backed off those remarks.
"I don't know, I think she's qualified, I guess," Trump said before adding that "that doesn't mean she's good."
He then said, "Bernie Sanders -- not me -- said she's not qualified. So now, I'm gonna say she's not qualified."
Trump also said Thursday he agreed with Sanders on another dig the Vermont senator made at Clinton: that she does not have the judgment to be president.
While Trump has been highly critical of the former secretary of state throughout his presidential campaign -- including knocking Clinton over her email scandal and calling her an "enabler" of her husband's alleged sexual abuse -- the New York real estate mogul had previously been effusive in his praise of the Clintons.
"Hillary Clinton, I think, is a terrific woman," Trump told Fox News in a 2012 interview in which he also praised Clinton for working "really hard" and doing a "good job" as secretary of state under President Barack Obama.
Trump has defended his previously affable relationship with the Clintons as just one of the many he maintained to benefit his business interests.
The Republican front-runner is increasingly turning his attention to what he hopes will be a general election battle between himself and Clinton.
But with the possibility of a contested Republican convention, Trump's final two opponents, Texas Sen. Ted Cruz and Ohio Gov. John Kasich, are refusing to leave the race despite being -- according to Trump -- "mathematically eliminated" from securing the nomination before the convention.
Kasich and Cruz both need to win more delegates than are available in the remaining primary contests to secure the Republican nomination on the first ballot. But as the possibility of a contested convention continues to loom, both men are planning for a scenario in which unbound delegates hand them the nomination in July.
"They should get out," Trump said Thursday night, echoing a pair of tweets earlier in the day in which Trump made the same call.