President Donald Trump took a break from the G-20 economic summit on Friday by tweeting his reaction to the second night of the Democratic debate, taking aim at two of the top candidates.

I am in Japan at the G-20, representing our Country well, but I heard it was not a good day for Sleepy Joe or Crazy Bernie. One is exhausted, the other is nuts - so what’s the big deal? — Donald J. Trump (@realDonaldTrump) June 28, 2019

Former Vice President Joe Biden has been the front-runner in every poll among the sprawling Democratic field, while Sen. Bernie Sanders of Vermont has also been a top-tier candidate.

The men stood next to each other during the Thursday night debate in Miami, which was carried live on NBC, MSNBC and Telemundo.

In an interview with Telemundo last week, Trump mentioned Biden and Sanders as potential adversaries he would prefer to spar with for the White House in 2020.

Trump, 73, who is running for his second term, has repeatedly attacked his older opponents' stamina. Biden is 76 and Sanders is 77.

"Bernie looks like he's had it," Trump told Telemundo. "Bernie looks crazy, but he always did. But he looks like a tired crazy right now."

Biden "looks like he's just exhausted," he added.

During Thursday night's debate, Biden mentioned Trump the most when he spoke, name-dropping him nine times, while Sanders mentioned him six times.