On Capitol Hill, three congressional Democrats have asked Defense Secretary Donald Rumsfeld to investigate the demotion of a senior civilian Army official who publicly criticized the awarding of a no-bid contract to Halliburton Co. for oil-related work in Iraq. The official — Bunnatine Greenhouse — had worked at the Pentagon for 20 years. Since 1998 she has served as the chief overseer of contracts at the Army Corps of Engineers. Last year Greenhouse went public to criticize the contracts involving Halliburton subsidiary Kellogg Brown & Root.