(Harrisburg) -- The list of Republican challengers to Pennsylvania’s Democratic U.S. Senator Bob Casey Jr. keeps getting longer. Among the announced candidates are tea party activist Laureen Cummings and businessman Steve Welch. Christopher Borick, a political scientist of Muhlenberg College, says no candidate or potential candidate immediately breaks from the pack in terms of name recognition and resources. "It’s hard to say what kind of talents and characteristics any of these possible candidates would bring simply because they haven’t had a big track record of being involved in races themselves," Borick says. Other challengers to Casey include retired military colonel John Vernon, pharmacist John Kensinger, lawyer Marc Scaringi, and businessmen Tom Smith and David Christian. In a recent poll, Casey’s approval rating was 46 to 30 percent.