Since her failed 2010 Senate bid, Coakley has spent $6,000 in leftover cash to promote a statewide bid for office, much of which appears to be a violation of campaign finance law.State law prohibits the use of federal campaign funds to support a state race. Coakley has consistently signaled that she is not interested in another Senate run and since 2010 had said that she would instead run for reelection as attorney general, before changing her mind and announcing a…