STEVE INSKEEP, host:
Those two Democrats, Barack Obama and Hillary Clinton, have divided their party by race, income and education. But nothing splits the Democratic vote as starkly as age. Here's NPR national political correspondent Mara Liasson.
MARA LIASSON: If you voted in none of the Democratic primaries or caucuses, your age was one of the most important predictors of your vote. The older you are, the more likely you were to vote for Hillary Clinton. The younger you are, the more likely you were to vote for Barack Obama. Just listen to these two undecided superdelegates - North Carolina Congressman Brad Miller, and then Massachusetts State Party Vice Chair Debbie Kozikowski.
Representative BRAD MILLER (Democrat, North Carolina): Within my own family, it breaks out almost the way the national polling does. My 93-year-old mother is for Hillary Clinton, and all my nephews and nieces are for Barack Obama.
Ms. DEBBIE KOZIKOWSKI (Massachusetts State Democratic Party Vice Chair): I have a 25-year-old son who's about to enter graduate school. He's very Obama-centric. And on the other hand, my mom, who's 76 years old, she has become very partisan in favor of Hillary Clinton.
LIASSON: Part of this divide is easily explained - Obama is younger. He's 46. Clinton is 60. But Obama has a special appeal to young people.
Mr. ZAHIR RAHMAN (Student, Wake Forest University): He's hip to our culture and kind of - and seems to know where young people are coming from.
LIASSON: That's Zahir Rahman, a sophomore at Wake Forest University in North Carolina, and - like so many of his peers - an Obama-enthusiast.
Mr. RAHMAN: The appeal of Barack Obama, someone who's new, offers this idea of hope and this idea of change, which really isn't attributed to either party or any of the other candidates that are running for the office.
LIASSON: But that's not the only reason young people vote for Obama, says Cliff Zukin, a professor of political science at Rutgers University. Unlike their baby boomer parents, he says, voters under 30 are incredibly tolerant.
Professor CLIFF ZUKIN (Political Science, Rutgers University): We have a woman candidate running against a black candidate, and I think if you were to advance that idea 25 years ago, people would have said that can't happen. And these young people today are so tolerant that they don't even think of that as an issue. I actually call them the whatever generation, in that they're non-ideological, they're non-judgmental, and the old-way of thinking about things -and that's by gender, by race, by groups - just doesn't make sense to them.
LIASSON: There have been youth candidates before in the Democratic Party - Gene McCarthy, George McGovern, Gary Hart. But this year, young voters are doing more than just getting excited about a candidate. They're actually turning out to vote. In primaries and caucuses all over the country, voters under 30 have doubled, and in some places tripled their turnout. Traditionally, young voters have very low turnout, but now their participation nationally is reaching their share of the population. And what could be even more significant, says Zukin, by big margins, they are Democrats.
Prof. ZUKIN: If young people continue to come into the electorate and identify as Democrats, there'll be a sea change in politics. What we've seen happen with George W. Bush is that he has made Democrats the same way Ronald Reagan made Republicans out of young people.
LIASSON: People tend to form their partisan preferences in their 20s and stick with them, so this trend could be the beginning of a long term political realignment. But in the short term, if Obama is the nominee, age will be a big issue this fall. Obama is already teeing up a classic generational challenge to John McCain.
Senator BARACK OBAMA (Democrat, Illinois; Democratic Presidential Candidate): Now, I believe John McCain is a good man and he is a genuine American hero, and we honor his half century of service to this nation.
LIASSON: A half century of service? That's a long time. Obama's message is simple. John McCain is old, very old. If he's elected, McCain would be the oldest first term president ever, and sometimes he makes a joke out of it.
Unidentified Female: By January 2009, you'll be 72 years old. How does it make you feel knowing that voters may reject you because they feel you're too old to be president?
(Soundbite of laughter)
LIASSON: The audience roared as McCain pretended to nod off in his chair. There'll be a lot more talk about age - funny and serious - if the general election match-up turns out to represent the biggest age difference in the history of American presidential campaigns.
Mara Liasson, NPR News, Washington.
STEVE INSKEEP, host:
The youth vote has affected the campaign differently in different states. And you can see a list of the top 10 states where Barack Obama has benefited by going to npr.org/elections.