AdvertisementWarren-Brown Pledge Keeps Attack Ads At BayMay 06, 2012Tovia SmithfacebookEmailDemocratic Senate candidate Elizabeth Warren holds up a poster of herself as Sen. Scott Brown, R-Mass., looks on during the annual St. Patrick's Day Breakfast in Boston on March 18. A civility pledge between the candidates has kept attack ads largely on the sidelines in their race. (AP)