IRVINE, Calif. (AP) - Illegal immigration emerged as a critical issue in the race to fill the nation's only vacant House seat, as an anti-immigration activist siphoned off enough votes from the GOP-backed favorite to force a runoff election. State Sen. John Campbell finished with 46 percent of the vote in Tuesday's special election in Southern California's heavily Republican Orange County, but failed to gain the majority needed to avoid a runoff. He will face the top vote-getters from four other parties in the Dec. 6 election. Second-place finisher Marilyn Brewer, a moderate Republican who drew 17 percent of the...