Heinz Kerry on Iraq, Vietnam, and Presidential Politics

May 6 -- Teresa Heinz Kerry is in a category all on her own among political wives. She's a woman who seems comfortable with contradiction — an environmental activist who owns three SUVs, for example.

Her husband, Sen. John Kerry, is the presumed Democratic presidential candidate, but Heinz Kerry was a registered Republican until just last year.

Beyond Heinz Kerry's substantial wealth — she's said to have a personal fortune of $500 million — her most notable trait as a political wife may be that she says exactly what she's thinking. "I'm a real person. I may not be what everybody would like to see, but it's real," she tells ABCNEWS' Barbara Walters in an exclusive interview for 20/20.

Widow of H. John Heinz III, she is no stranger to the political spotlight and the scrutiny that comes with it. Her first husband, H. John Heinz III, sole heir to the Heinz ketchup and food fortune, served nearly 20 years in Congress — as a Republican congressman and senator from Pennsylvania — before his death in a 1991 plane crash.

And she's made it known over the years that she's never been particularly thrilled at the thought of being first lady.

When people asked her late husband to seek the presidency, she said, "I used to say 'over my dead body,' you know, because I was so terrified of it."

Indeed, she tells Walters she had no idea that Kerry was interested in a presidential bid when she married the Massachusetts senator in 1995. And she says she struggled to support his decision to seek the White House.

"It's something that you really have to come to terms with if it's not kind of a passion of your own," she said.

After some soul-searching, she tells Walters, she told Kerry she would support his presidential aspirations. "I said, 'I've thought about this a lot and I really have no right to be in your way.' … That means that I have an obligation to help. Because you can't do it halfway.