Of the four big elections happening on Tuesday, the closest by far will be in Pennsylvania.
In the Keystone state, Democratic Sen. Arlen Specter is locked in a dead heat with Rep. Joe Sestak in a primary challenge for Specter's Senate seat, and Democrat Mark Critz and Republican Tim Burns are facing off in an equally tight special election for the late John Murtha's 12th-district House seat.
The other races aren't as close. In Arkansas, Sen. Blanche Lincoln leads her primary against Lt. Gov. Bill Halter by nine percentage points; in Kentucky's Tea-infused Republican Senate primary, Rand Paul leads Secretary of State Trey Grayson by double digits.
But Pennsylvania's two races are too close to call.
In the state's southwest corner, different polls show a different leader. The Republican Burns led Critz 48-47 in an automated Public Policy Polling survey released yesterday. Critz, meanwhile, led 44-38 according to a Susquehanna poll released May 12.
In the Senate primary, Sestak leads Specter 42-41 in a Quinnipiac survey released today--well within the poll's +/13.2% margin of error. An Allentown Morning Call survey released yesterday shows the candidates tied.
Sestak has gained significant ground since mid-April in that race. See below a Pollster.com graph of how the race has polled: