MILWAUKEE (AP) – U.S. Senate candidate Tommy Thompson is making an appearance in front of the Milwaukee Press Club.  A panel of professional journalists will interview the former Republican governor on Friday.   Thompson and Democratic candidate Tammy Baldwin are vying for the seat that became open following the retirement of Democrat Herb Kohl.   A new Marquette University Law School poll released Wednesday showed Baldwin with a 48 percent to 44 percent lead over Thompson, a gap that falls in the poll’s 3.3 percentage point margin of error. She held a 9-point lead in the same poll two weeks ago.   The latest poll of 894 likely voters was done Sept. 27 through Sunday.  The general election is Nov. 6.