Kentucky: Polls close 6:00 PM ET (areas within Eastern time zone) and 7:00 PM ET (areas within Central time zone).
• KY-Sen (R): Senate Minority Leader Mitch McConnell's high profile and occasional gestures of bipartisanship earned him some enemies from within his own party and many tea party groups vowed to unseat him in a primary. For a time it appeared that wealthy businessman Matt Bevin could give McConnell a real race.
However, it was never clear that enough Republican primary voters were ready to oust McConnell to give Bevin a shot. Bevin also had his own flaws: He was put on the defensive after it was revealed that he had signed a letter supporting the 2008 TARP bill. Every poll has shown McConnell leading Bevin by a wide margin, and it looks like Bevin has run out of time. The winner of the primary will face Democratic Secretary of State Alison Lundergan Grimes, who should have no trouble against her little-known primary opponents.
Head below the fold for more races to watch Tuesday.
To help keep track of the many Georgia House primaries, we've included the above interactive map.
• GA-Sen (R): Five credible Republicans are competing to succeed retiring Sen. Saxby Chambliss, and a runoff is all but assured. Most polls show former Dollar General head David Perdue (who is also a cousin of former Gov. Sonny Perdue) favored to advance to July. However, Perdue did himself no favors a week before the primary when he suggested it might be necessary to raise taxes. Needless to say this is not exactly what Republican primary voters like to hear, and it's possible Perdue's comments could cost him on Tuesday.
It looks like a tight race for the other runoff spot between Rep. Jack Kingston and former Secretary of State and 2010 gubernatorial candidate Karen Handel. Two other congressmen, Phil Gingrey and Paul Broun, are also running. Both of them have a long history of making offensive statements and Democrats would love to face either of them in the general. Unfortunately, while a surprise is certainly possible, polling shows them both missing the runoff. The eventual Republican nominee will face former non-profit CEO Michelle Nunn, who has only token primary opposition in the Democratic primary.
• GA-01 (R): Six Republicans are running to succeed Jack Kingston in this reliably red coastal district. Only three of them have spent any real money: state Sen. Buddy Carter; physician Bob Johnson; and venture capitalist John McCallum. A runoff is very likely and it looks like Tuesday will be a contest between the three of them to secure the two available spots. Johnson complicated his chances after he declared he'd "rather see another terrorist attack," than allow the TSA to "indoctrinate" Americans. State Rep. Jeff Chapman is also running, but his fundraising has been close to non-existent and it would be a major surprise if he advanced.
• GA-04 (D): Four-term Rep. Hank Johnson faces a well-known primary challenge from former DeKalb County Sheriff Tom Brown in this heavily Democratic seat. Brown was widely praised after he reformed the very corrupt sheriff's department, and he has attacked Johnson for not securing enough federal money for the district. Johnson has the support of President Obama, which should give him a boost. Johnson and Brown are the only two candidates so (barring an extremely unlikely exact tie) whoever wins the most votes Tuesday will secure the nomination.
• GA-10 (R): Seven Republicans are running to succeed Paul Broun in this safely red district. Trucking company owner Michael Collins, who is also the son of former Rep. Mac Collins, has spent the most here. Collins should be favored to advance to a runoff, but winning outright on Tuesday will be tough. State Rep. Donna Sheldon is the only other candidate to spend at least $50,000 and she is probably the best positioned to secure the other runoff spot. Pastor and radio host Jody Hice (who ran in the old Seventh District back in 2010) also may have a shot here.
• GA-11 (R): Six Republicans are running for Phil Gingrey's safely Republican seat in Atlanta's northern suburbs. The best known is probably former Rep. Bob Barr, who has returned to the GOP after serving as the Libertarian Party's 2008 presidential nominee. However, Barr's fundraising has been pretty weak and many Republican voters may not appreciate his apostasy. The other main contenders look like state House Majority Whip Ed Lindsey, state Sen. Barry Loudermilk, and businesswoman Tricia Pridemore. This is another crowded race where a July runoff looks very likely.
• GA-12 (R): Five Republicans are lining up to try to unseat Democratic Rep. John Barrow in this conservative seat. Businessman and 2012 primary runner-up Rick Allen looks like the frontrunner, though he'll need a lot to go right for him to win the nomination outright. Allen's main opponents look like businessman Eugene Yu and state Rep. Delvis Dutton. Republicans are expected to target Barrow no matter who wins the nomination, but Barrow has proven time and again that he's no pushover.
Pennsylvania: Polls close 8:00 PM ET.
• PA-Gov (D): Four Democrats are running for the right to take on the very vulnerable Republican Gov. Tom Corbett. While Rep. Allyson Schwartz and state Treasurer Rob McCord started out as the best-known contenders, businessman and former state Revenue Secretary Tom Wolf quickly changed that. Wolf began spending his considerable wealth on ads early this year and never let up, vaulting him into the lead. Polls show Wolf far ahead of Schwartz, McCord, and former state EPA Secretary Katie McGinty. Unless there's a surprise, Wolf should easily win the nomination on Tuesday.
• PA-08 (D): Two Democrats are competing to face Republican Rep. Mike Fitzpatrick. Veteran Kevin Strouse is the preferred choice of most of the Democratic establishment and has outspent businesswoman Shaughnessy Naughton. However, Naughton looks more formidable than initially expected and may be able to pull off an upset. The winner will start out as the underdog against Fitzpatrick, though the district is swingy enough that either Democrat has a chance to unseat him.
• PA-13 (D): Four Democrats are running for this safely blue open seat that includes parts of Philadelphia and its Montgomery County suburbs. Each of the four looks like they have a chance to win. Former Rep. Marjorie Margolies has the support of the Clintons (she is also Chelsea Clinton's mother-in-law) but has been criticized for running a disorganized campaign. Physician Val Arkoosh is wealthy and well funded. State Sen. Daylin Leach, who has been endorsed by Daily Kos, has been appealing to liberal voters and also has plenty of resources. State Rep. Brendan Boyle looks like the most socially conservative of the bunch, but he has the backing of many influential Philadelphia ward leaders and unions. This looks like it will be one of the most exciting and unpredictable races on Tuesday.
Arkansas: Polls close at 8:30 PM ET. Note that in any race where no one wins more than 50 percent of the vote, the top two vote-getters will advance to a June 10 runoff.
• AR-02 (R): Three Republicans are running to succeed GOP Rep. Tim Griffin. Banker French Hill quickly outspent state Rep. Ann Clemmer and veteran Conrad Reynolds, and it looks like the nomination is Hill's to lose. The winner will face Democrat and former North Little Rock Mayor Patrick Henry Hays in November.
• AR-04 (R): Freshman Republican Rep. Tom Cotton is giving up this seat to run for the Senate. Two Republicans are running: state House Majority Leader Bruce Westerman and businessman Tommy Moll. A recent poll gave Westerman a huge lead over Moll, but Moll had enough money available late in the race to make things interesting. The winner will face Democrat and Clinton-era FEMA Director James Lee Witt.
Idaho: Polls close at 10:00 PM ET (areas within Mountain time zone) and 11:00 PM ET (areas within Pacific time zone).
• ID-Gov (R): Republican Gov. Butch Otter won a pretty weak 55 percent in the primary during his 2010 re-election and he faces a credible challenge from state Sen. Russ Fulcher. Fulcher, who has the backing of Rep. Raul Labrador, has been hitting Otter for setting up health-care exchanges. Still, it looks like Fulcher is the clear underdog. Two other Republicans are also running: While they won't win, they helped give us one of the most entertaining political debates ever.
• ID-02 (R): Republican Rep. Mike Simpson's close relationship with Speaker John Boehner and occasional moderation has earned him a challenge from lawyer Bryan Smith. Smith and his allies have portrayed Simpson as insufficiently conservative: Simpson has fired back by calling Smith a trial lawyer, which is not a good label to be stuck within a GOP primary. In the last weeks of the race the well-funded Club for Growth stopped advertising for Smith, which is not a good sign for the challenger.
Oregon: Polls close at 11:00 PM ET.
• OR-Gov (R): Democratic Gov. John Kitzhaber is not particularly high on Republican target lists, but six Republicans hope they can unseat him. There's no public polling here but state Rep. Dennis Richardson is probably the favorite. Richardson is the only Republican in the race who holds elected office and he holds a clear fundraising edge over the rest of the field.
• OR-Sen (R): Freshman Democratic Sen. Jeff Merkley is also a tough Republican target, but two credible Republicans are running for the right to oppose him. The party establishment appears to be backing physician Monica Wehby over state Rep. Jason Conger: Wehby has also outspent Conger and holds a clear lead in what little polling there is.
• OR-05 (R): Democratic Rep. Kurt Schrader occupies a swingy district, and two Republicans are competing to face him. Luckily for Team Blue neither former Congressional aide Ben Pollock nor Clackamas County Commissioner Tootie Smith have raised much money, and Schrader should be favored over either of them.