Complex sentence: Marty is also a well-known opponent of public funding for stadiums for professional sports teams and was outspoken in his criticism of the recent proposals for new stadiums for the Minnesota Twins and Minnesota Vikings.
Split into simpler sentences: Marty is also a well-known opponent of public funding for stadiums and professional sports teams. He was outspoken in his criticism of the recent proposals for new stadiums for the Minnesota Twins and Minnesota Vikings.