So, too, has a striking increase in the number of Californians who blame illegal immigration for the state's problems. "There is more unity among Republicans in this state on illegal immigration than on anything else, including taxes," said Tom Hudson, chairman of the Republican Party in Placer County, near Sacramento, one of the most conservative counties in the state. Among the GOP candidates, former Massachusetts Gov. Mitt Romney has seized the issue with vigor, and U.S. Rep. Tom Tancredo of Colorado has made border security the centerpiece of his long-shot campaign, even airing a campaign commercial comparing illegal immigration with...