Donald Trump refused to shake hands with Jeb Bush after Saturday night's GOP debate, the former Florida governor said on Monday.

"It was ugly," Bush said on MSNBC's "Morning Joe." "Part of it was related to the need to make sure people knew that Donald Trump is not a conservative and he got angry and kind of lost it a little bit. I can't describe it, I went and shook hands with everybody at the end and I think he saw me coming to do it and he walked away, so he may be still angry about it."

The comment is spillover from a remarkably contentious debate Saturday, characterized by Trump's attacks on Bush and on Texas Sen. Ted Cruz, and punctuated by his scolding of a debate audience that often booed his criticism of Jeb and George W. Bush.

Trump repeatedly knocked Jeb Bush's foreign policy during a discussion of how the United States should defeat the Islamic State, a line of attack that culminated in Trump claiming that George W. Bush lied about Saddam Hussein's weapons of mass destruction program in order to instigate a war with Iraq. "I want to tell you: they lied," he said. "They said there were weapons of mass destruction. There were none and they knew there were none. There were no weapons of mass destruction."

That provoked a biting response from Jeb Bush. "When Donald Trump was building a reality TV show, my brother was building the security apparatus that kept us safe," the former Florida governor said.

At another point in the debate, Trump said Bush was weak on immigration. "The weakest person on this stage by far on illegal immigration is Jeb Bush," he said. "He is so weak on illegal immigration it's laughable, and everybody knows it."

When Trump hit Bush, his rival had an opportunity to respond. "If you want to talk about weakness, you want to talk about weakness? It's weak to disparage women. It's weak to denigrate the disabled. And, it's really weak to call John McCain a loser. ... That is outrageous. The guy's an American hero."