With four days remaining until election day, the Democratic presidential contest in California has boiled down to a battle for delegates between Sens. Hillary Rodham Clinton and Barack Obama.
California, with 441 delegates at stake, is the biggest single prize in the nation's presidential primary, but don't look for either candidate to make a clean sweep Tuesday.
Unlike the Republicans, the Democratic Party does not allow winner-take-all primaries, which can allow a front-runner to quickly dominate the field. Instead, the party's complex rules for allocating delegates somewhat favors the second-place finisher.
Both campaigns are focusing their efforts on maximizing their delegates -- Clinton by building a strong statewide organization and Obama by targeting certain parts of the state.
"This is turning out to be an incredible, very exciting primary," said veteran Democratic campaign manager Darry Sragow, who is not aligned with a candidate. "I think the voters are engaged and fascinated."
That may be true -- polls certainly indicate a high level of interest -- but the process for allocating delegates might leave some people baffled too.
Of the 441 delegates that the state will send to the Democratic convention in Denver this summer, 71 are so-called super-delegates who have a vote by virtue of the office they hold.
Of the remaining 370 delegates that will be allocated by voters, 241 will be divided among the state's 53 congressional districts and allocated to candidates based on the vote they receive.
But not all congressional districts are equal. Some will have as few as three delegates, some as many as six. The number depends on how heavily Democrats have turned out in the past.
In one peculiarity of the process, a candidate who wins by a big margin in one district could end up with fewer delegates than a candidate who wins by a narrow margin in another.
For example, in a district with four delegates, a candidate who wins 62% of the vote would get two delegates -- so would a candidate who wins 38% of the vote.
But in a district with three delegates, a candidate who wins 50.1% of the vote would get two delegates, and a second-place finisher with 49.9% of the vote would get one.
In practical terms, this means that congressional districts with three or five delegates offer candidates a shot at a bonus -- the chance to pick up an extra delegate with a low margin of victory. The chance of picking up extra delegates in districts with four or six delegates is lower.
"There's some real kinky math in it," said Bill Carrick, a veteran political consultant who is not connected to either campaign. "The end result is that even if you lose in a two-candidate race, you can get an even split in delegates. And the winner can pick up the extra delegate in the odd-numbered districts."
Mitchell Schwartz, California campaign director for Obama, said he has a map on his wall of the state's 53 districts and has selected about 20 where he thinks the Illinois senator could pick up an extra delegate.
Schwartz said the campaign has "shifted resources in the field" to try to capitalize on the quirks in the rules. "It's different from winner take all," he said. "You can lose a state and still pick up a bunch of delegates."
But Ace Smith, Clinton's California campaign director, said the key to the New York senator's campaign is a strong statewide effort that will affect the allocation of delegates in every district, not targeted ones. And he insists that the Clinton campaign is well ahead of Obama in the state.
He said Hillary and Bill Clinton, both popular in California since the days of his presidency, have "crisscrossed the state" during frequent visits over the last year.
Hillary Clinton's high-profile backers include Sen. Dianne Feinstein, Los Angeles Mayor Antonio Villaraigosa and former Los Angeles Lakers great Magic Johnson.
A Los Angeles Times Poll conducted last week showed Clinton leading Obama by 17%, although most of that poll was conducted before Obama's victory last Saturday in South Carolina's primary, which may have given him a boost nationwide.
"We've been working in California since May," Smith said. "We have a field operation second to none. We have the support of almost every significant public official in the state. We are beating him every step of the way. We are all over the state."
In an attempt to catch up, Obama took to television first with ads in the Bay Area. Schwartz said the campaign wanted to reach early vote-by-mail voters, who are more prevalent in the Bay Area than in other parts of the state.