The GOP front-runner waded into the contentious fight between the two Democratic 2016 hopefuls in a tweet early Saturday morning.
"Bernie Sanders says that Hillary Clinton is unqualified to be president. Based on her decision making ability, I can go along with that!" Trump said.
Trump was referencing comments
Sanders first made on Wednesday evening, when the Vermont senator said he did not think his opponent was "qualified" for the presidency based on the super PAC money she receives as well as her votes for the Iraq War and free trade agreements.
The fight got more heated as the week went on, with former President Bill Clinton saying he thought there was a "subconscious" gender bias behind Sanders' comments -- a charge Sanders denied.
"I appreciate Bill Clinton being my psychoanalyst," Sanders joked in an interview with CNN's Jake Tapper.
Sanders didn't reference Trump's tweet while speaking at a rally in New York City on Saturday, but did allude to the infighting among Democrats.
"When we began this campaign, everyone was really, really nice to me because they thought we were irrelevant," Sanders said.
Hours before weighing in on the Clinton-Sanders dispute, Trump weighed in on the presidential fight on his own side of the aisle.
Trump tweeted, "Isn't it a shame that the person who will have by far the most delegates and many millions more votes than anyone else, me, still must fight."
Trump has called out perceived unfairness at many points in his quest for the Republican nomination. Last Sunday, Trump said one of his rivals
, Ohio Gov. John Kasich, "shouldn't be allowed to run."
The mogul's comments about Kasich came just days after he again refused to rule out
an independent presidential bid should he be denied the Republican nomination.
Trump has been quiet on the campaign trail over the past couple of days, tweeting Friday
that he's "catching up on many things" now that he's back in his home state of New York, which holds its Republican primary on April 19.