WASHINGTON INSIGHT

MR. REFORM: Sources say Senate Majority Leader George J. Mitchell (D-Me.), who is spearheading legislation to curb the influence of money in politics, spent most of a recent week in Florida raising $400,000, mostly from fat cats. He told friends that he aims to raise $2 million by the end of the year in order to scare away potential challengers in the 1994 elections. . . . A spokeswoman said Mitchell doesn’t disclose fund-raising figures until they are reported to the Federal Election Commission.