The political arm of MoveOn.org is spending far more money attacking Republicans than on behalf of the Democrats it supports, campaign filings show. Since last year, Federal Election Commission (FEC) filings show the group has spent nearly 90 percent of more than $3 million in so-called independent expenditures to target a dozen Republican candidates, including presidential aspirants Rudolph W. Giuliani, a former mayor of New York City, and Arizona Sen. John McCain. "The political and practical reality is that negative ads work, and they work better than positive ads," said Kenneth A. Gross, former associate general counsel for the FEC....