Sestak beats Specter in PA,; Paul beats Grayson in KY

Upstart Senate candidates claimed two stunning victories in primary elections Tuesday night as Pennsylvania Rep. Joe Sestak denied incumbent Democrat Arlen Specter renomination to a sixth term and Kentucky insurgent Rand Paul easily bested establishment favorite Trey Grayson for the Republican Party's Senate nod.

In the evening's third key Senate race, Arkansas Sen. Blanche Lincoln clung to a slim lead of a few thousand votes over Lt. Gov. Bill Halter with nearly 85 percent of the vote counted in the state's Democratic primary, but will face an expensive and potentially dangerous June 8 runoff since neither candidate will reach 50 percent of the vote.

Insurgents didn't completely rule the night, however. Democrat Mark Critz, a former Hill aide, defeated Republican Tim Burns in the special election for the Pennsylvania congressional seat of the late Rep. John Murtha. Both parties invested millions in the race — viewed as a bellwether election for the fall campaign.