BOSTON — A new WBUR poll (PDFs – topline, crosstabs) of the special Massachusetts U.S. Senate election finds it wide open on both the Democratic and the Republican sides. U.S. Rep. Ed Markey, of Malden, leads his Democratic rival, U.S. Rep. Stephen Lynch, of South Boston, by 11 percentage points. On the Republican side, former U.S. Attorney Michael Sullivan, of Abington, has the lead over both Norfolk state Rep. Dan Winslow and Cohasset private equity manager Gabriel Gomez.