http://www.publicintegrity.org/2015/06/11/17470/white-house-race-has-already-sparked-1-million-negative-ads
"To date, nearly all of the negativity has been directed at Democratic Party frontrunner Hillary Clinton, who announced her candidacy in mid-April.
This month alone, Clinton has been attacked by the Republican National Committee and a host of other conservative groups, including the Stop Hillary PAC and the Citizens United Super PAC."
