PITTSBURGH — GEORGE BUSH, denying that his latest travels for the Republican Party signaled the start of his campaign for reelection, defended his domestic record and vowed not to "let a handful of Democrats set the agenda for this country."President Bush rejected charges that he has turned his back on the nation's disadvantaged, pointing to his initiatives to improve education, protect the environment, fight crime, and spur the economy. In addition to addressing a Pittsburgh fund-raiser this week for former Attorney General Dick Thornburgh, who is running for the United States Senate, Bush stopped in Louisville, Ky., and Nashville, Tenn. Clearly annoyed over claims that his recent domestic trips marked the unofficial start of his reelection campaign, Bush lashed out at reporters at a White House news conference. "I realize it's that time of year, and as each Democrat gets out there and starts announcing [for the presidency] it's going to increase the propensity in the media to say ... everything I do is political," said Bush. "I expect people to say it's political, but that's just the time of year, just the season, but I'm not going to worry about it." The president then took a few jabs at his would-be opposition. m not going to let a handful of Democratic candidates ... set the agenda for this country. They weren't elected to do something - I was, and I'm going to to keep on trying to do it." A senior White House official said Bush probably would not formally announce plans for a second term until after he delivers the State of the Union address next January. Five Democrats have already entered the race.