Paul Hackett, an Iraq war veteran and popular Democratic candidate in Ohio's closely watched Senate contest, said yesterday that he was dropping out of the race and leaving politics altogether as a result of pressure from party leaders. Mr. Hackett said Senators Charles E. Schumer of New York and Harry Reid of Nevada, the same party leaders who he said persuaded him last August to enter the Senate race, had pushed him to step aside so that Representative Sherrod Brown, a longtime member of Congress, could take on Senator Mike DeWine, the Republican incumbent. Mr. Hackett staged a surprisingly strong...