The colorful brochure from Mitt Romney's presidential campaign looks like many of the political fliers flooding Iowa mail boxes this time of the year. But there is a difference. The piece is Romney's first to single out his rivals by name, a shift that shows him becoming more aggressive in the final weeks before the Jan. 3 caucuses. The mailing juxtaposes photos and quotes from Romney showing his support for a federal constitutional amendment to define marriage as the union of one man and one woman with photos and quotes showing Rudy Giuliani, John McCain, and Fred Thompson all oppose...