MUSKEGON, Mich. -- President Bush chided Sen. John Kerry and fellow Democrats on Monday for asserting that Republicans will undermine Social Security, calling the strategy ''the most tired, pathetic way to campaign for the presidency.'' Traveling by bus through the southwest corner of this battleground state, Bush tried to improve voters' perceptions of his domestic policies by condemning Democrats for going negative -- even as he held Kerry's plans up to the harshest possible light. ''I'm running against a fellow who has got a massive, complicated blueprint to have our government take over the decision making in health care,'' the...