Video: Marco Rubio's 10 greatest slams against Donald Trump

When Florida Sen. Marco Rubio was running for president, he didn't mince words when attacking frontrunner Donald Trump. And Trump didn't hesitate to fire back. Here are 10 of Rubio's best punches.

1. "Hand size"

In response to being called "little Marco," Rubio took a aim at Trump's hand size during a rally in Salem, Va., on Feb. 28, saying "I'll admit, the guy, he's taller than me. He's like 6'2", which is why I don't understand why his hands are the size of someone who's 5'2". Have you seen his hands? ... And you know what they say about a man with small hands. You can't trust 'em. You can't trust 'em."

Days later in a March 3 debate, Trump responded: "Look at those hands, are they small hands? And, he referred to my hands — 'if they're small, something else must be small.' I guarantee you there's no problem. I guarantee."

RUBIO'S CHALLENGE: Support Donald Trump now without hurting his own reelection chances — or his political future

2. "Will never be the nominee"

"I don't care if I have to get in my pickup truck and drive around the country like I did when I ran for the Senate," Rubio said Feb. 28 on Fox News Sunday. "Donald Trump will never be the nominee of the party of Lincoln and Reagan."

3. "Erratic individual"

"This is the most important government job on the planet. And we're about to turn over the conservative movement to a person that has no ideas of any substance on the important issues," Rubio said in an interview Feb. 26 on CBS This Morning. "The nuclear codes of the United States — to an erratic individual — and the conservative movement — to someone who has spent a career sticking it to working people," he added.

Later that day, Trump tweeted a misspelled response: "Lightweight Marco Rubio was working hard last night. The problem is, he is a choker, and once a choker, always a chocker! Mr. Meltdown."

4. "The most vulgar person"

"Donald Trump has been perhaps the most vulgar — no, I don't think perhaps — the most vulgar person to ever aspire to the presidency in terms of how he's carried out his candidacy," Rubio told CNN's Alisyn Camerota March 4 on New Day.

5. "Getting harder every day"

On March 12 in Largo, the Saturday before the Florida primary, Rubio described Trump's rallies as "frightening, grotesque and disturbing."

He also discussed his growing apprehension of supporting a nominee like Trump.

"I mean, I already talked about the fact that I think Hillary Clinton would be terrible for this country, but the fact that you're even asking me this question," he said, pausing before continuing. "I still at this moment continue to intend to support the Republican nominee, but it's getting harder every day."

6. "A fake university"

During a heated exchange Feb. 25 at a GOP debate in Houston, Rubio attacked Trump saying, "Well I don't know anything about bankrupting four companies. You bankrupted four companies. I don't know anything about starting a university that was a fake university. A fake university. There are people that borrowed $36,000 to go to Trump University and they're suing him now. $36,000 to go to a university that's a fake school. And you know what they got? They got to take a picture with a cardboard cutout of Donald Trump."

7. "A con artist"

"There is no way that the party of Reagan and the conservative movement — I'm gonna allow it to be taken over by a con artist. He says I'm a choker, he's a con artist," Rubio told George Stephanopoulos Feb. 26 on ABC's Good Morning America.

8. "Worst spray tan in America"

At a Feb. 27 rally in Kennesaw, Ga., Rubio attacked Trump's appearance: "He put out a picture of me having makeup put on me at the debate, which is amazing to me that the guy with the worst spray tan in America is attacking me for putting on makeup. Donald Trump likes to sue people, he should sue people for whoever did that to his face."

9. "What's his plan?"

"You might not be aware of this Donald, because you don't follow this stuff closely, but here's what happened," Rubio said during the Feb. 25 debate, calling out Trump for not having a plan to handle health care.

He explained how Republicans wiped out bailouts that were originally included in Obamacare.

"Here's what you didn't hear in that answer. This is important, guys, this is important thing. What is your plan? I understand the lines around the state, whatever that means. ... What is your plan? What is your plan on health care? You don't have a plan," Rubio said to Trump.

Trump responded: "The biggest problem he's got is he doesn't know. I watched him meltdown two weeks ago with Chris Christie. I gotta tell you the biggest problem he's got is he really doesn't know about the lines."

10. "Sweat mustaches"

The next day, Rubio mocked Trump at a Dallas rally: "Last night at the debate during one of the breaks, two of the breaks, he went backstage. He was having a meltdown. ... He had one of those sweat mustaches. Then, he asked for a full length mirror. I don't why, because the podiums go up to here," Rubio said while gesturing towards his chest. "...Maybe to make sure his pants weren't wet. I don't know.

"Then I see him pacing back and forth and then he's huddled in the corner talking to someone. He's like waving his arms up and down and the person is trying to calm him down."