DAVID GREENE, HOST:
Here are some of the signs that Bernie Sanders's presidential campaign is for real - large turnout at events, campaign cash coming in, poll numbers on the rise and now add this - the front-runner for the Democratic nomination was forced to talk about him. Hillary Clinton gave her first national television interview yesterday since launching her campaign, and the conversation turned very quickly to Vermont Senator Bernie Sanders. Here's NPR's Tamara Keith.
TAMARA KEITH, BYLINE: Feel the Bern, that's how Bernie Sanders supporters describe what's been happening. The independent senator says it's a political movement...
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UNIDENTIFIED GROUP: (Chanting) Bernie, Bernie, Bernie.
KEITH: ...Reflected in his campaign fundraising totals - $15 million so far - and the large crowds at his events, like Monday night in Portland, Maine.
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BERNIE SANDERS: In case you didn't notice, this is a big turnout.
KEITH: Seventy-five hundred people in a packed arena. There were 10,000 in Madison, Wis. Polls show Sanders gaining on Hillary Clinton. When Clinton sat down with CNN, the first question was about Sanders's momentum.
(SOUNDBITE OF CNN INTERVIEW)
HILLARY RODHAM CLINTON: Well first of all, I always thought this would be a competitive race, so I am happy to have a chance to get out and run my campaign as I see fit and let other candidates do exactly the same.
KEITH: Clinton and her advisers have been saying from the start they expected a tough primary, even when no one really believed that they meant it. Jennifer Palmieri, with her campaign, went on MSNBC earlier this week.
(SOUNDBITE OF MSNBC INTERVIEW)
JENNIFER PALMIERI: Of course we're worried about him. This is an election and he is doing well. And - so we'll have to make our case - but we knew this was going to happen.
KEITH: Part of that is downplaying expectations. But Sanders's blunt message about income inequality is resonating with a certain segment of Democratic voters, including millennials. At Clinton's big campaign kickoff rally in New York, William Arnone raved about the candidate, but his 21-year-old daughter...
WILLIAM ARNONE: She broke my heart the other day when she said, Daddy, I met Hillary, I love her. I know you do, too. I like Bernie Sanders. So I said, well, that's OK, Allison. But let's get real at some point (laughter).
KEITH: Still, Hillary Clinton remains, without a doubt, the front-runner. There are reasons for that. The Democratic establishment is behind her, everyone knows who she is, and there's the money. Clinton raised three times as much as Sanders in the early months of the campaign.
ELAINE KAMARCK: Usually, for all the drama in between, frontrunners win, OK (laughter)?
KEITH: Elaine Kamarck is the author of the book, "Primary Politics," and was a super delegate for Hillary Clinton in 2008.
KAMARCK: The question is, for those people who don't like Hillary Clinton, there's always a sort of anybody-but movement.
KEITH: Kamarck says Sanders has consolidated the support of the anybody-but voters. Mo Elleithee agrees. He's executive director of the Georgetown Institute of Politics and Public Service. In 2008, he worked for Clinton, and in the year 2000, he worked on the campaign of another anybody-but candidate, former Senator Bill Bradley.
MO ELLEITHEE: We actually, at one point, were leading Al Gore.
KEITH: It didn't last, but Elleithee argues, it made Vice President Gore a stronger candidate.
ELLEITHEE: Just like the heavyweight boxer should never go into a championship bout without having had a sparring partner - a legit sparring partner - that's the role that Bradley helped play for Gore, and I think that is a role that Bernie can play for Hillary. And, you know what? If she ends up stumbling, he can be there to pick up the pieces.
KEITH: The only role Sanders says he wants to play is nominee. Clinton's team would surely love to knock him out early, but they're building an organization designed to take the fight as far as it needs to go. Tamara Keith, NPR News. Transcript provided by NPR, Copyright NPR.