Thomas A. "Buck" Riley Jr., chairman of the Pennsylvania Convention Center Authority board since May 2007, is resigning as of May 15.

Riley informed his 14 fellow board members of his plans in an email sent early this afternoon.

A Republican and a Paoli lawyer who is chief executive officer of his own law firm, he cited no reason for leaving other than having a full plate. "The last four years as chairman have been most challenging and the equivalent of more than a second full time job," he wrote. "The Center is now entering a new phase of its life and it's time for a new Chairman to take the reins."

Under state legislation that governs the authority, a new chairman will be elected by the remaining board members. In the interim, lawyer Carl Singley, a Democrat who is the authority's vice chairman, will act as chairman.

Riley's departure means there will be up to four new faces on the board. Besides Riley, City Councilman Frank DiCicco will soon leave since he is retiring from Council in early January. Gov. Corbett has also yet to name his two appointees to the board, potentially replacing Michael Masch and Gregory Fox, both appointees of former Gov. Ed Rendell.

Riley leaves after overseeing the completion of the Convention Center's $786 million expansion - the largest public works project in state history. However, his resignation now means he won't be there as chairman to celebrate the new building's grand opening in early July.

Riley succeeded Mayor Nutter as board chairman.

"With important issues under current consideration e.g. implementation of the Crossroads Report, labor negotiations and marketing issues to be considered, " Riley wrote board members, "I respectfully suggest it's important for the board to elect a new Chairman sooner than later."

Click here for's politics page.