Romney sidesteps tax dispute; Gingrich dives in KASIE HUNT,Associated PressTHOMAS BEAUMONT,Associated Press DES MOINES, Iowa (AP) — Mitt Romney refused to be pinned down Wednesday on how Congress should break an impasse that threatens to raise taxes for 160 million workers — the latest pressing policy debate the Republican presidential hopeful has sidestepped. Rival Newt Gingrich, in contrast, castigated Congress for "an absurd dereliction of duty." With less than two weeks before the Iowa caucuses, the two rivals exchanged ever sharper words over a barrage of negative ads coming from Romney's allies as they took a divergent approach on the payroll tax dispute deadlocking Washington.