Mitt Romney has attempted to shake his image as a "Massachusetts moderate" at the national level, while Republican Sen. Scott Brown is hoping the label will stick to him as he runs for re-election in the heavily Democratic state. The Massachusetts Democratic Party, however, is using a new ad to paint Brown as anything but a centrist.The ad, released Wednesday, focuses on Brown's ties to Romney, who has sought to portray himself as a dyed-in-the-wool conservative to win the Republican presidential nomination.