Who's ahead right now in the race for the Democratic presidential nomination? It depends on how you count.

The closest thing to an official scorecard in the Democratic race is the number of pledged delegates each candidate has won. The tally, according to the Associated Press, is 1,488.5 pledged delegates for Barack Obama and 1,333.5 for Hillary Rodham Clinton. After last week's Pennsylvania primary, Obama still has a lead of 155 pledged delegates. That is not a formidable edge. But Democratic Party rules that award delegates proportional to the vote make it very difficult for Clinton to catch up.

A contender needs 2,025 delegates to win the nomination. Only 408 pledged delegates are left to be chosen. So neither candidate can reach a majority with pledged delegates alone. The superdelegates will determine the winner.

The 795 superdelegates are under a lot of pressure to follow the popular vote. "We think that if ... we end up having won twice as many states and having the most votes, then we should end up being the nominee," Obama said in Indiana last week. But who has the most votes?

The vote totals for the 30 primaries held so far (not including Florida and Michigan, which violated party rules) are 14.4 million for Obama and 14.1 million for Clinton. Obama won the popular vote in those primaries by slightly more than 341,000. So how can Clinton say what she said on April 23 in Indianapolis: "I'm very proud that, as of today, I have received more votes by the people who have voted than anybody else"? Because she also said, "If you count, as I count, the 2.3 million people who voted in Michigan and Florida, then we are going to build on that."

Some Clinton supporters argue that it would be fair to include the Florida votes because both candidates' names were on the ballot and no one campaigned in Florida. "I believe that Senator Clinton needs to win the popular vote," New Jersey Gov. Jon Corzine said. "That includes the votes in Florida, in my view, but not in Michigan."

"We think that if ... we end up having won twice as many states and having the most votes, then we should end up being the nominee."

If you add in the Florida votes, Obama's lead in the popular vote shrinks to about 46,000 (14.97 million votes for Obama, 14.92 million for Clinton). In Michigan, Obama took his name off the ballot. So he got no votes. Clinton received about 328,000. If you add in the Michigan votes, Clinton goes into the lead, 15.3 million to 15.0 million.

But Obama would argue, what about the caucuses? He won most of those. Nine caucus states report straw vote totals for each candidate. In three other caucus states (Iowa, Maine, and Nevada), votes for each candidate must be estimated from the total turnout and the delegate counts. Washington state and Texas held both a primary and caucuses. Only the primary votes are added to the totals to avoid counting voters twice (in Texas, caucus participants were required to vote in the primary earlier that day). If we take the 30 undisputed primaries and add in the number of votes cast in 12 caucus states, Obama leads by more than half a million votes (551,000).

Obama is also ahead in the number of states won--not counting Florida, Michigan, or Texas. Why not Texas? Because it had both a primary and caucuses, and Clinton won the primary but Obama won the caucuses. Washington state also held a primary and caucuses, but no delegates were awarded in its primary. Obama won its caucuses, so Washington is considered an Obama state. The bottom line: Obama has won 27 states to Clinton's 14.

But Clinton supporters argue that their candidate has won bigger states. That is just barely true, if you don't count Florida or Michigan or Texas. Obama has won states with a total of 202 electoral votes. Clinton has won states with a total of 206. What do electoral votes have to do with winning the nomination? Nothing. It's simply an argument that the superdelegates may hear from the Clinton camp: "See? We've done better in the states that will matter more in November."

This article appeared in the Saturday, May 3, 2008 edition of National Journal.

Want to stay ahead of the curve? Sign up for National Journal’s AM & PM Must Reads. News and analysis to ensure you don’t miss a thing.