California Gov. Jerry Brown on Thursday warned that Hillary Clinton should be ready for anything ahead of the general election in November.
The Democrat explained in an interview on "CBS This Morning" that he learned from his father, who also served as governor of California, not to take an election for granted.
"What my father, another governor of California, always said, never be complacent, never be taken for granted. Be on alert, you've got to run as though you're behind so you win at the end," Brown said. "She should be ready for anything. She should be ready for an onslaught, a vituperation, and insult and negativity."
Democrats need to take this election seriously, he said, because there's always unpredictability in politics.
"Politics of the assassins is unpredictability, surprise, and that's more true today than it's ever been in the past," he said. "This is a competitive election, you never know what is going to show up in the world of events, terrorism and all the rest. I'd say Democrats need to be on guard, on alert, and on the attack."
Brown, who spoke at the Democratic National Convention in Philadelphia on Wednesday, sat near President Bill Clinton during many of the speeches that night in the arena.
Asked what some of his comments were on speeches, Brown said the former president was aghast at Trump's remarks Wednesday morning when he invited Russia to track down his wife's 30,000 emails she deleted from when she was secretary of state.
"I think he's shocked at Trump's calling for espionage, I think he really felt that really went over the line. He said that to me," he said.
Pointing out that Trump said in a Fox News interview that he was being sarcastic, Brown said, "Whether it was sarcastic or not, I mean he was making a declarative sentence, but I think that it's the loose-cannon quality that over time is going to reinforce an impression that I think is accurate."
Brown said that what Trump said was a crime and another indication of "instability" that will wear down Trump between now and November.
Since he ran against President Clinton in 1992, Brown said that the Democratic Party is "far more inclusive and diverse" and said "I think it's pretty unified."