Primary races in Pennsylvania, Kentucky and Arkansas have election watchers nationwide on the edge of their seat. Party-switching five-time incumbent Senator Arlen Specter is facing an unexpected challenge from Rep. Joe Sestak in the Pennsylvania Democratic primary. Retiring Republican Sen. Jim Bunning’s pick to succeed him, Trey Grayson may be upset by Tea Party favorite Rand Paul in Kentucky. And, Arkansas incumbent Sen. Blanche Lincoln’s numbers are slipping as national unions pump money into the state to fund her Democratic opponent. Will an anti-incumbent mood prevail?
Ken Rudin, political editor for NPR and writer of the Political Junkie blog
Alex Isenstadt, national political reporter for Politico