SACRAMENTO (AP) - Conservative activists vowed Thursday to sue the state if Gov. Arnold Schwarzenegger proceeds next week with his $920 million, 20-year borrowing plan to pay off part of one year's pension obligations. Attorneys for the Pacific Legal Foundation said Schwarzenegger's widely expected move would violate a state constitutional ban on governments borrowing more than $300,000 without a popular vote. The foundation represents a Fullerton taxpayers group aiming to derail the idea. Last year, courts cited the constitutional ban in striking down a similar borrowing plan by then-Gov. Gray Davis. "This is a clone of last year's borrowing ploy,"...