The former vice president of the United States worries about nuclear war and rising sea levels brought on by global warming.

He'd back U.S. Sen. Amy Klobuchar if she ran for president, thinks U.S. Rep. Tim Walz is a good candidate for governor, is outraged by President Trump, and calls sexual harassment a real problem but says the accused deserve due process.

Minnesota's Walter Mondale turned 90 on Friday, and he remains as conversational and as liberal as ever. He doesn't feel like 90, he said in an interview, and he still enjoys talking politics with his DFL friends — among them Klobuchar, Gov. Mark Dayton and new U.S. Sen. Tina Smith.

"I don't have to go out and do the speeches anymore, I can just give my message to people who I know and who I love who are in politics now," Mondale said.

On Wednesday, he was in Washington, D.C., "thrilled" to be walking down the aisle of the Senate chamber with Smith, who considers Mondale a mentor, on her way to be sworn in as a senator.

"It brought back all my years there and in Washington," he said, "the things we got done in the civil rights revolution and so on. I thought I was going to be cool about it. It really had an effect on me."

Did he get emotional? "Well, Norwegian emotional," Mondale grinned. "A lot of friends came up and said hello to me."

He is dismayed by growing polarization in Washington, D.C. "You saw that last session where they passed a tax bill and tried to repeal Obamacare and all without a single Democrat, not even consulted."

Back when he was a U.S. senator, he said, "The moderates on both sides worked together."

Not surprisingly, President Donald Trump doesn't impress him.

"I think he's an outrage," Mondale said. "Honesty is where you begin, I don't care who you are … He has lied three or four times every day. It's expected. You can't expect this. And you can't respect it."

Mondale said he worries Trump "says things that could trigger responses by others" resulting in a nuclear war.

If we get into such a war with North Korea, he added, "there could be millions of Japanese, South Koreans, and hundreds of thousands of American soldiers killed in the process."

Mondale said the U.S. needs to join "with our friends around the world" to deal with global warming. "President Trump and his people believe that the global environmental risks are fake, don't exist. There is not a not a scientist in America who has studied this who agrees with him."

Mondale said the investigation by special prosecutor Robert Mueller into Russian interference in the 2016 election should be allowed to work its course. "I think that he is a serious person with a lifetime of law enforcement experience, digging deeply and carefully into facts."

On the subject of sexual harassment, Mondale said, "Women shouldn't have to live with that. It should be stopped. Having said that, I'm worried about due process. … When people hand out complaints through the fence, unnamed, we have no way of evaluating the truth of that or not."

Mondale, who is retired from the Dorsey & Whitney law firm, was interviewed at his office there.

"They give me an office and a great secretary and it works out fine," Mondale said. "They'll probably kick me out one of these days and I'm going to defend it on the grounds that you can't pick on the aged."

An invitation-only birthday bash is planned at the University of Minnesota on Jan. 13. One of the speakers will be former President Jimmy Carter, who chose Mondale as his vice president. They served one term from 1977 to 1981. Carter is 93.

"We are now the oldest surviving presidential and vice presidential team in American history," Mondale said. "Eight years ago we surpassed Adams and Jefferson. We're still going. I think in a few years, they'll retire the trophy."

Randy Furst • 612-673-4224 Twitter: @randyfurst