** Nevada Senate: Senate Majority Leader Harry Reid is vulnerable -- of that there is no dispute. But whether Republicans can nominate a candidate with the muster to beat him remains to be seen. Sue Lowden had been seen as that candidate, but her comments about bartering for health care have turned her into a bit of a national punch line. Danny Tarkanian, son of the renowned UNLV hoops coach, has not made a strong impression in his own right. Sharron Angle is picking up some steam in the final month, but still is largely unknown statewide. Then again, a generic Republican may be just what the party needs given Reid's diminished standing.

RCP Average: Lowden +7.5 | RCP General Election Rating: Lean Republican

** Nevada Governor: This has been one of the great under-covered races of the cycle thus far. Gov. Jim Gibbons (R) barely crossed the finish line in 2006 after reports about an alleged assault of a cocktail waitress, among other issues, hobbled him in the final weeks. In office, he's battled with his own party on policy and had a very public divorce, all as Nevada's economy cratered. Several Republicans are challenging him in the primary, led by former Attorney General Brian Sandoval. If Gibbons loses, which is considered likely, he'd be the first incumbent governor to be ousted in a primary since Alaska's Frank Murkowski (R) finished third in 2006 -- behind one Sarah Palin. Rory Reid (D), son of the embattled senator, is unopposed; Democrats would much prefer to face Gibbons, of course.

Latest Poll: Sandoval +18 | RCP General Election Rating: Lean Republican

** Iowa Governor: Terry Branstad (R) is one of five former governors running for a chance to reclaim his old job. The former four-term leader is considered the favorite in this race, but it's no sure thing. Bob Vander Plaats is putting up a strong fight, and has been endorsed by 2008 presidential caucus winner Mike Huckabee. Mitt Romney actually endorsed Branstad just today, so we have the added bonus in this race of a potential 2012 tea leaf-reading. Gov. Chet Culver (D), who's seen his numbers plummet in the past year, is likely to be renominated but the final number will be an interesting first indication of his vulnerability. Vice President Biden helped Culver kick off his re-election bid just today.

RCP General Election Rating: Likely Republican

** South Carolina Governor: In another important early presidential nominating state, we have an even more vibrant Republican primary. Four major candidates are looking to replace Mark Sanford (R) in Columbia: Lt. Gov. Andre Bauer, Attorney General Henry McMaster, Rep. Gresham Barrett, and state Sen. Nikki Haley. Haley captured headlines late last week for endorsements by Sarah Palin and Jenny Sanford, the ex-wife of the incumbent. There's been a real dearth of public polling in the race, but that will likely change once we get through today's contest. Democrats don't have much hope of putting up a fight in November, but State Superintendent of Education Jim Rex may have an edge in that primary as the only statewide officeholder.

RCP General Election Rating: Likely Republican

** Maine Governor: To put it simply, this is a complete toss up race. With Gov. John Baldacci (D) term limited, there are at least a dozen candidates running for the seat, including independent candidates in a state that has elected them before. Given the state's moderate-to-liberal tilt, Democrats have an early edge on paper but we'll need to re-evaluate once the primary is over.

RCP General Election Rating: Lean Democratic

** Also voting June 8: North Dakota and South Dakota. The only major draw is in the latter, where several Republicans are running for the right to challenge Rep. Stephanie Herseth-Sandlin (D) in November, when she may face her toughest challenge to date. RCP now classifies that contest as a Toss Up.

There's also an active GOP primary for governor, as incumbent Mike Rounds (R) is term limited. That race is considered Safe Republican.