LEWISTON, Maine (NEWS CENTER) — Former Maine U.S. Senator George Mitchell is on the campaign trail for Hillary Clinton. He told voters gathered at the Franco Center in Lewiston Tuesday about his experience in government with her.

In an interview with NEWS CENTER afterwards, Mitchell said he didn't expect Donald Trump to become the Republican nominee this year. He said there are clear differences between Trump and Clinton that make it easy to pick who should be president.

In his talk, he touched upon a few of those difference, including Clinton's temperament. He said she's more qualified and committed to take on issues like climate change and preventing the use of nuclear weapons. Mitchell said he's met Trump a few times, but the two didn't interact much besides saying, "Hello" and "How are you?"

The senator also thinks American politics has been this heated and divisive before, but in year's past, most of that came out in writing instead of on television or social media where it’s more visible.

“American politics has always been rough and tumble,” he said. “A professor at the University of Maine, Amy Fried, wrote an article some time ago describing the presidential campaign of 1800, when two men who are now national icons — Thomas Jefferson and John Adams — ran against each other. Some of the things that their supporters said about the candidates were very rough, very insulting, even by current standards.”

Clinton supporters listening to Mitchell said he's motivated them to go out and spread his message about Clinton.

“Many of us are energized by hearing Senator Mitchell speak,” said Barbara Trafton, a Clinton campaign volunteer who attended Mitchell’s event. “We're going to be out doing canvassing in neighborhood, speaking with our co-workers and our neighbors and our friends.”

Other Democrats will be in northern New England later this week.

Vice President Joe Biden will be campaigning for Clinton in New Hampshire Thursday.