While Congressional races in Indiana drew attention two weeks ago, a brighter national spotlight is shining on Senate primary votes Tuesday in Pennsylvania, Arkansas and Kentucky. Part of the intrigue is whether a couple of Democratic incumbents will become lame ducks.

The focus is on senators Blanche Lincoln of Arkansas (challenged by Lt. Gov. Bill Halter) and Arlen Specter of Pennsylvania (facing Rep. Joe Sestak).

Runoffs are possible for both parties in Arkansas as a third candidate could keep Lincoln or Halter from getting 50% of the vote. On the Republican side, Rep. John Boozman is the favorite but there are eight other candidates on the ballot and he was polling below the 50% mark.

Those polls place Boozman ahead of both Democrats in general election matchups, but Lincoln has a huge advantage in cash on hand.

Specter’s much-publicized departure from the GOP came, at least in part, because he believed he wouldn’t win a primary battle against former Rep. Pat Toomey. Now he is in a close battle against Sestak, who has successfully used the message that he is the real Democrat in the race. The two Democrats and Toomey also have substanial bankrolls for the fall.

Kentucky features a pair of close battles. Ophthalmologist Rand Paul, a Tea Party favorite, is leading Republican establisment favorite Trey Grayson (current secretary of state). On the Democrat side, two current top state officials — Attorney General Jack Conway and Lt. Gov. Daniel Mongiardo, are in a dead heat.

Two incumbent primary victims thus far have been Sen. Bob. Bennett (R-Utah) and Rep. Alan Mollohan (D-West Virginia). I’ll take a guess that Specter might just joing them. Either way, Tuesday will be another lesson about the anti-incumbent mood among voters.