Jeanine Pirro, the high-profile district attorney from suburban Westchester County, will seek the Republican nomination to challenge Sen. Hillary Rodham Clinton's bid for re-election next year, a top adviser said Monday. The adviser, speaking only on condition of anonymity to allow Pirro to make the announcement herself, said the district attorney planned to tour the state Wednesday to formally announce her decision. Pirro began calling top New York Republicans Sunday night to tell them of her decision, said the adviser and another top Republican source familiar with her plans. There was no immediate comment Monday from Pirro.