The biggest single campaign donor in this year’s race for a seat on Pennsylvania’s Supreme Court is now aiming to endorse a candidate for governor and, with $20 million in a bank account, it could be a transformative endorsement. Members of the double-digits-deep field of Republican candidates say they have interviewed with board members of the group — Commonwealth Partners Chamber of Entrepreneurs — in hopes of getting support or an endorsement. A relative newcomer to Harrisburg’s deep ranks of advocacy organizations, the group’s political action committees have become a conduit for campaign cash from billionaire Jeffrey Yass.