Donald Trump’s spokesperson, Katrina Pierson, told Breitbart News Saturday that Wisconsin is “the last competitive state at this level.” If that is what the Trump campaign truly believes, the frontrunner is in trouble in California.

It is true that Sen. Ted Cruz (R-TX) will have few chances to win outright after Wisconsin. He is 289 delegates behind Trump and has almost no hope of catching up. He will be mathematically eliminated from winning the party nomination outright on April 19, when New York votes and Trump sweeps up its 95 delegates in the winner-takes-all primary. But Cruz will continue to fight to deny Trump an outright majority and force a contested convention.

Trump needs 485 more delegates to reach the 1,237 delegates needed for a majority. Yet as fivethirtyeight.com notes, he has fallen off pace since mid-March, when a series of self-inflicted wounds damaged his campaign.

Unless he can improve dramatically in the coming weeks, Trump will fall short. His best chance for a large delegate haul is California, which has 172 delegates, most of which are awarded on a winner-takes-all basis by congressional district. While recent polling shows the race tightening in California between Trump and Cruz, Trump leads Cruz in every region of the state except the rural, conservative Central Valley, where there are few congressional districts.

The problem for Trump is that Cruz is far more organized. Last Thursday, Cruz met personally with hundreds of his potential delegates in the state. The Cruz campaign understands that in places with few Republicans, such as San Francisco, a few votes can make the difference — and can earn just as many delegates as in heavy Republican areas.

Given the current polling, there are three foreseeable outcomes in California: a large Trump win, a narrow Trump win, and a narrow Cruz win. A large Trump win could mean hitting the 1,237 threshold, and winning the Republican nomination. A narrow Trump win could mean falling short of the 1,237 threshold, but still putting Trump in position to make a bid for the nomination by entering into a unity agreement with either Cruz or Ohio Gov. John Kasich.

A Cruz win would most likely mean defeat for Trump’s overall presidential ambitions. Though Trump would almost certainly still hold a delegate lead, his loss would signal rejection by the party as its nominee. Cruz might hope to win the nomination in a floor fight at the Republican National Convention in Cleveland. More likely, he would be able to trade his delegates’ support to another nominee in return for a guaranteed vice presidential spot.

Trump has time to catch up with Cruz in California — nearly nine weeks — but he has to work hard, or he will fall.