David Jackson

USA TODAY

MOON TOWNSHIP, Pa. — The presumptive 2016 Republican presidential nominee hit a couple of potential swing states Saturday to strike back at his critics — including the 2012 Republican presidential nominee.

In travels to Florida and Pennsylvania, Donald Trump attacked Mitt Romney and others who say the businessman's "trickle-down racism" and harsh comments about women will drag the GOP down to defeat in the November election against Democrat Hillary Clinton.

Romney "choked like a dog" in his 2012 loss to President Obama, Trump told supporters at the airport near Pittsburgh, and is now attacking him unfairly. Earlier in the day, in Tampa, Fla., Trump called Romney "a stone cold loser."

The attacks came a day after Romney echoed his refusal to endorse Trump, saying he lacks the temperament to be commander-in-chief.

USA TODAY exclusive: Hundreds allege Donald Trump doesn’t pay his bills

“I don’t want to see a president of the United State saying things which change the character of the generations of Americans that are following,” Romney said on CNN. “Presidents have an impact on the nature of our nation, and trickle down racism and trickle down bigotry and trickle down misogyny — all of these things are extraordinarily dangerous to the heart and character of America.”

The nominee-in-waiting is under attack from a variety of Republican lawmakers, particularly over his claim that a federal judge's "Mexican heritage" makes him biased in a fraud case involving the now-defunct Trump University.

Trump has vowed not to discuss the judge again, and stuck to that pledge Saturday, though he did criticize "politically correct" public officials who criticize some of the things he says.

"It's like a bunch of babies," Trump said, "a bunch of dumb babies."

For the Record's week in review: Clinton's killer week

It's very unusual for a previous presidential nominee to criticize a current nominee, and vice-versa. It probably hasn't happened to this extent in the Republican Party since 1912, when ex-President Theodore Roosevelt ran against successor William Howard Taft on a third-party ticket, helping elect Democrat Woodrow Wilson that year.

Romney has ruled out a third-party bid in 2016 but told attendees at a conference he sponsored Saturday that he is saddened by how many Republicans have rallied behind Trump. He said the GOP's troubles are "breaking my heart."

Trump also attacked Romney via social media, tweeting Saturday that Romney "had his chance to beat a failed president but he choked like a dog. Now he calls me racist — but I am least racist person there is."

The New York businessman said his emphasis on jobs will unify the country, telling supporters at the airport in Pittsburgh: "White, black ... we're going to bring everybody together."

Trump takes aim at Clinton in appeal to evangelicals

Trump also paid tribute to the voters in Florida and Pennsylvania, states that may be essential to his efforts to defeat Clinton in November.

Florida is a must-win state for any Republican candidate. Trump is also hoping to break through in Democratic-leaning states like Pennsylvania, which the Republicans haven't carried in a presidential election since 1988.

Trump is in the midst of a weeklong national tour that also includes potential swing states like New Hampshire, Nevada, and Arizona.

The schedule includes a Monday speech in New Hampshire attacking the current Democratic candidate as well as ex-President Bill Clinton.

Trump also turns 70 years old on Tuesday, a fact noted Saturday by supporters in Pennsylvania and Florida who shouted "Happy birthday" at him.

"I don't want to hear about it," Trump joked in Tampa, though he added that "I feel like I'm 35. That's the good news."

