California is not exactly the GOP’s idea of home turf.

Republican presidential candidate, former Massachusetts Gov. Mitt Romney speaks during a campaign stop at William Jewell College on Tuesday, in Liberty, Mo. (AP Photo/Evan Vucci)

California’s June 5 primary, despite being the second-to-last contest, is looking more and more like it may determine whether Mitt Romney can win the Republican nomination or whether the party goes to its August convention without a nominee.

“If Gingrich drops out and Santorum can go at Romney one on one, it could be competitive all the way to California, in which case California would pretty much decide the nomination,” said John Ryder, a Republican National Committeeman from Tennessee who is an expert on the delegate process.

Part of the reason is the state’s sheer size. Because states are given three delegates to the Republican National Convention for every congressional district they have, California has a whopping 172 delegates. That’s more than 15 percent of the delegates needed to win the nomination.

California is technically a winner-take-all state, but because basically all of its delegates are awarded by congressional district, there is the possibility that they get sliced up any number of ways.

That said, Romney is a strong early favorite in the state, leading every poll there this year and by 20 points in the most recent poll. What’s more, the state’s more moderate brand of Republicanism and highly urban population seem to play right into his hands.

California is still the Wild West at this point; none of the candidates have set up much of a campaign in the state. Romney and Newt Gingrich have been there to raise money, and but the June 5 primary is so far away and the state is so big — not to mention that the race could be over by then — that’s it’s hard to devote a lot of effort there right now.

“None of the candidates has infrastructure here except Romney — and that is left over from four years ago,” said California GOP consultant Matt Rexroad. ”Romney will probably look to focus on the areas of the state where he did well four years ago.”

Romney didn’t win the state four years ago, but he did have a respectable showing, trailing John McCain by 8 percent in the state’s Super Tuesday primary.

But even in his respectably showing, Romney won just four of the 53 congressional districts, and thus he won just 12 delegates, with the rest (158) going to McCain. It was McCain’s single biggest delegate haul and played a big role in icing the nomination for the Arizona senator.

It also proved that Romney doesn’t need to score a blowout to win nearly all of the state’s delegates. He just needs a consistent and significant victory.

Romney is hoping for a similar result, albeit much later in the process. But as long as his opponents are still in the race, it’s highly likely that the state will matter.

California’s primary is June 5 — before only Utah’s primary on June 26. We pretty much know Romney is going to sweep all 40 of Utah’s delegates — he will win the heavily Mormon state, which is winner-take-all — so assuming Romney still has competition in early June, we will know exactly how many delegates he needs on June 5 to win the nomination.

Other states will vote that day — most notably New Jersey — but California will account for most of the delegates at stake.

In addition, it appears diffcult (for now) that Romney will secure the nomination before California. He would need to win more than two-thirds of the delegates between now and June 5 to make that day’s contests moot.

“There is a growing likelihood it will matter,” said Ron Nehring, a former state GOP chairman. “My unscientific guesstimate is there is a 33 percent chance it will be needed to give someone the nomination.”

In other words, it’s time to start looking at California as a real potential battleground.

It may decide the Republican nominee.

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