MICHELE NORRIS, host:
For the Democrats, the magic number of delegates needed to secure the presidential nomination is 2,025. But neither Obama nor Clinton has gotten anywhere near that number in state voting. And increasingly, it looks like the superdelegates could decide the Democratic race.
Here's NPR's David Welna.
DAVID WELNA: The 796 superdelegates comprise nearly 20 percent of this year's Democratic delegates. They are the members of Congress, governors, party elders, and activists. Party officials created superdelegates in the early 1980s, says nomination expert Henry Brady of the University of California at Berkeley, so that things such as a deadlock convention could be resolved by party insiders.
Professor HENRY BRADY (Political Science and Public Policy, University of California-Berkeley): There was a concern that somehow there wasn't enough adult supervision, actually, by the rest of the party. And so, one to get more of the party politicos enclosed into the process was to create these superdelegates.
WELNA: More than half the superdelegates have already endorsed either Clinton or Obama. Because Clinton has snagged more such endorsements, she's slightly ahead of Obama today in the total delegate tally. Even though he's actually won more regular pledge delegates, both are assiduously courting still undecided superdelegates. One is Ohio Democratic senator Sherrod Brown.
Senator SHERROD BROWN (Democrat, Ohio): Well, I think the superdelegates will pretty much reflect what the voters have done, and I think by August one of the candidates will have begun to get momentum and have a substantial lead. And I think the superdelegates will, in all likelihood as we should, have reflect that.
WELNA: And what if it doesn't happen?
Sen. BROWN: Well, I think it will. I don't what if, what if, what if.
WELNA: Brown won't say when he'll make an endorsement, but another senator, Florida Democrat Bill Nelson has already come out for Clinton. He wants this race decided before it gets to the party's convention in Denver this August.
Senator BILL NELSON (Democrat, Florida): I don't think we want to go back to those wealing, dealing, smoke-filled backroom days.
WELNA: So you think the superdelegates really shouldn't be the deciding factor in this.
Sen. NELSON: Well, right now. It looks like that's the only choice.
WELNA: It's a choice Minnesota Democratic senator Amy Kloburchar, who has yet to endorse a candidate, also thinks should be made before Denver.
Senator AMY KOLBURCHAR (Democrat, Minnesota): I will not go through the summer, I can tell you that, without endorsing a candidate. I'm not a big believer in smoke-filled rooms.
WELNA: Barack Obama, for his part, told reporters last Friday that the superdelegates should be guided by the results of the primaries and caucuses.
Senator BARACK OBAMA (Democrat, Illinois; Presidential Candidate): My strong belief is that if we end up with the most states and the most pledge delegates from the most voters in the country, that it would be problematic for the political insiders to overturn the judgment of the voters.
WELNA: But Obama also added that superdelegates should consider who'd best be able to defeat John McCain in November. Hillary Clinton, for her part, told reporters today that superdelegates should exercise independent judgment.
Senator HILLARY CLINTON (Democrat, New York; Presidential Candidate): You can look at this state by state and see that there are a lot of people in states that I've won, who support him. A lot of people in states that he won, that support me. That's what superdelegates are supposed to do.
WELNA: If anyone knows the sting of a superdelegate vote, it's former senator Gary Hart. Today, he's an Obama supporter, but in 1984, neither he nor Walter Mondale had won a majority of delegates going into the Democratic Convention that year.
Mr. GARY HART (Former Colorado Democratic Senator; Obama Supporter): I think virtually every superdelegate voted for Walter Mondale in the teeth(ph) of polls the weekend before the convention showing that Fritz ran 15 to 17 points behind Reagan, and I ran 4 to 5 points behind Reagan, they still voted for Mondale and Mondale lost very badly.
WELNA: If superdelegates must break such a stalemate this year, it's not clear how bound these supposedly free agents will feel to promises they've already made.
David Welna, NPR News, the capital.