03/16/2012 09:18 am ET Updated May 16, 2012

For First Time in Half Century, California's "Late" Primary Could Decide GOP Race

California, a national trendsetter culturally, has never mattered much in Republican presidential politics -- at least not since 1964, when far-right conservative Barry Goldwater used his victory in the state's primary contest to capture the GOP nomination before losing in a landslide to incumbent Democrat Lyndon Johnson later that same year.

But the Golden State seems destined to regain the political spotlight in 2012. That's because its June 5th primary is the last of the major delegate-rich contests in a GOP race that's beginning to look hopelessly deadlocked. Neither of the two front-runners, Mitt Romney and Rick Santorum, is likely to have a majority of the 1,144 delegates needed to win the party nomination by the time they compete for the 172 delegates up for grabs in the nation's most populous state. It's the single-largest GOP delegate prize, 17 more than Texas and and 77 more than New York. No other state even comes close.

Currently, according to Wall Street Journal tallies, Romney has 495 delegates, compared to 252 for Santorum, 131 for Gingrich, and 48 for Ron Paul. In theory, if the former Massachusetts governor can win just 60% of the remaining delegates, he will sew up the nomination before the GOP holds its nominating convention in Tampa on August 29. Santorum, by contrast, would have to win 80% of the remaining delegates to win the nomination outright, and Gingrich, a whopping -- and at this point, unattainable -- 90%.

But with Gingrich and Santorum both in the race, and still competing so strongly, it could well prove difficult for Romney to obtain that 60%. In fact, the more Santorum keeps winning primaries, as he did in Alabama and Mississippi this week, the more he's likely to gain credibility in states where Romney largely had the field to himself -- or least a clear edge. While the surging Santorum may not secure the nomination outright, he could well deny it to Romney.

Some delegate-rich states are still clearly Romney's to lose. New Jersey (also on June 5), with 50 delegates, is a winner-take-all-contest, and New York (April 24) becomes winner-take-all if the victor wins at least half the popular vote. That means Romney, who enjoys a near 2-1 polling lead in New York, conceivably could win most or even all of the 145 delegates at stake in these two contests.

But the same is true for Santorum. In winner-take-all primaries in Wisconsin (April 3), North Carolina and his home state of Pennsylvania (April 24), Santorum could win 169 delegates, off-setting Romney's victories elsewhere. Romney has yet to win a Southern state, which gives Santorum a clear edge in North Carolina. And the latest polls in Pennsylvania have Santorum winning by an overwhelming margin there.

In many of the remaining contests, proportional divisions of the delegates are not likely to strongly favor either candidate.

Which brings us to California. It's not a winner-take-all state outright, but it's not, strictly speaking, a proportional representation state, either. The delegates are divided among the different congressional districts so, if you win a district, you can still win delegates, even if you lose the state popular vote. The catch is, whoever wins the district popular vote, regardless of the actual vote margin, gets all of the delegates assigned to that district. In other words, the system is still winner-take all -- just at the district level.

In fact, the California primary has previously functioned as a winner-take-all contest -- or close to it -- because the winning candidate statewide often wins all of the congressional districts, even if their margin of victory statewide is fairly small. In 2008, McCain beat Romney 42%-35% in the popular vote statewide but ended up with 90% of the delegates -- or 155 -- because he also carried nearly all of the districts. The same thing could happen in 2012.

Until recently, it didn't appear that Santorum had much of a shot at winning California. However, recent polling now has him in striking distance of Romney -- and closing. For example, the latest Field Poll of California voters, conducted in mid-February, showed Romney leading Santorum 31 percent to 25 percent. Paul was favored by 16 percent, and Gingrich trailed with 12 percent. Other polls show the race even tighter.

So one possible scenario is this: Romney and Santorum split the winner-take-all contests more or less evenly, and Romney wins 60% of the delegates in the proportional contests leading up to California. That might give him between 1,000 and 1,100 delegates, close to but still short of the 1,144 majority needed to win. In this setting, what happens in California -- and how it ends up dividing its 172 delegates -- could be the deciding influence.

What's amazing -- and perhaps ironic -- about this year's potential late-breaking race in California is that the state decided not to move up its primary date to give it more preponderant influence like so many other states have. In fact, four years ago, then-California governor Arnold Schwarzenegger twisted arms to have his state's primary moved all the way up to "Super Tuesday" on February 5, only to find that 20 other states managed to do the same thing. With literally half the GOP delegates at stake on a single day, the impact of McCain's California victory, while significant, became significantly diluted.

But not this year. Even pushed way back to its traditional spot in the primary calendar, California is suddenly shaping up as potentially the most critical GOP battleground of 2012. Other states that moved their contests up this year lost half of their delegates as a penalty; having wisely chosen not to, California retains all of its delegates in tact. Which means it's the last big blockbuster prize of 2012. Its 172 delegates -- 15% of the majority required, if won outright -- could either seal the deal for Romney, or deny him the majority he needs to ward off a fierce and unpredictable delegate battle at the convention.

Either way, there's a precedent in the making here. Critics of the primary system have complained for years about the inordinate influence of smaller, rural conservative states like Iowa and New Hampshire whose demographics are far from representative of the nation but whose early primary results have heavily shaped who ends up winning each party's nomination. And despite periodic calls for reform, the primacy of the traditional primaries has remained largely unchanged.

This year, though, events themselves may be conspiring to allow the largest, most populous and most culturally diverse state in the nation cast the deciding ballots. If so, the primary system as we've known it may never be quite the same.