His delegate lead growing, Mitt Romney gently nudged his Republican opponents toward the sidelines on Wednesday and said he was on track to wrap up the presidential nomination before the party convention next summer. Rick Santorum and Newt Gingrich paid him no mind, vowing to fight on in a campaign marked by persistent ideological divisions. If anything, the political maneuvering intensified as the marathon pointed toward contests in five states over the next week. Romney's campaign purchased television advertising time in Alabama according to campaign sources, as it pursued a breakthrough in the party's Southern base....