Story highlights Trump is the pick of 39% likely Republican voters, while Cruz has the support of 32%

The poll also notes wide differences among Republican voters across key regions of the state

Washington (CNN) GOP front-runner Donald Trump is leading Texas Sen. Ted Cruz in California, a new poll shows, one of the final primary contests before the Republicans head to the party's convention in July.

Trump is the pick of 39% likely Republican voters, while Cruz has the support of 32%, according to a poll from the Field Research Corporation in California. John Kasich is in third place at 18%, while 11% are undecided.

Cracks in GOP rank-and-file also are reflected in the poll, as nearly 4 in 10 California Republicans (38%) say they would be "dissatisfied" or "upset" if Trump became their party's nominee, and nearly as many (34%) say this about Cruz.

The poll also notes wide differences among Republican voters across key regions of the state. Trump is holding the lead among likely Republican voters in two regions: the nine-county San Francisco Bay area and Southern California outside of Los Angeles County. While Cruz is leading in Los Angeles County and those living in the state's vast but sparsely populated interior, support for Kasich is evenly spread across the state, although he is stronger in the San Francisco Bay area.

This could be significant as the regional differences in preferences could split the state's allocation of its 172 delegates in the GOP convention.

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