(AP) WASHINGTON - Bowing to political realities, Democratic presidential candidate John Kerry has canceled plans to begin broadcasting television commercials in Arizona, Arkansas, Louisiana and the perennial battleground of Missouri. The decision to shrink his political playing field reduces Kerry's strategic options — at least for now — in the homestretch of the campaign. George W. Bush won all four states in 2000, and Kerry can't win the White House without taking a state or two from the Republican incumbent. While pulling back from some states that Bush carried, Kerry is still strongly competing in several GOP-leaning battlegrounds, including Ohio,...