Hard-fought GOP Senate primaries in Iowa and Mississippi are among the most closely-watched races Tuesday night, as voters head to the polls in eight states.
The Mississippi race has attracted widespread national interest, with six-term incumbent Sen. Thad Cochran and Tea Party favorite Chris McDaniel in a deadlocked race noted for its under-handed politics and potential to decide which political party will control the upper chamber in November.
The other races are in Alabama, California, New Jersey, Montana, New Mexico and South Dakota.
In Mississippi, the 76-year-old Cochran essentially led the race from the start despite allegations that he was having an inappropriate relationship after he brought a female Senate aide on numerous official trips overseas. Cochran has denied any such relationship.
McDaniel, a state senator, managed to narrow the lead in the closing weeks, even after an Easter Sunday incident in which a supporter took a picture of Cochran’s wife, who suffers from dementia, in a nursing home.
Police eventually arrested four men in connection with the incident and said they intended to use to the picture to advance the allegations about the relationship.
McDaniel, who has called the incident reprehensible, received support from such groups as Freedom Works, the anti-tax organization Club for Growth and the anti-establishment Senate Conservatives Fund.
The winner must take 50 percent of the vote to avoid a runoff.
Tea Party-backed candidates failed last month in Kentucky, losing to Senate Majority Leader Mitch McConnell, and in Georgia, to GOP Rep. Jack Kingston, but defeated 17-term incumbent GOP Rep. Ralph Hall in Texas.
Kingston is now in a July runoff with GOP businessman David Perdue.
In Iowa, a candidate who garnered national attention with a campaign ad about castrating hogs is leading the pack in the GOP primary for the Senate seat.
State Sen. Joni Ernst has a double-digit lead in most polls. However, she will need to attract more than 35 percent of the vote to win the party nomination outright and avoid a convention nominating process in which delegates pick the nominee.
She is running in a crowded field for the first open Senate seat in the state in three decades. Her closest challenger is former executive Mark Jacobs, with 18 percent of the vote, according to an averaging of polls by the website RealClearPolitics.
In the hog ad released in March, Ernst playfully suggests her experience on her family’s farm castrating pigs will translate to her cutting “pork” in Congress, pledging to "make 'em squeal" in Washington. The national attention helped her languishing fundraising efforts and put her ahead of Jacobs in the polls.
The GOP primary winner is expected to face presumptive Democratic nominee Rep. Bruce Braley for the seat of retiring Democratic Sen. Tom Harkin.
California has eight congressional primaries, with Democratic Gov. Jerry Brown’s re-election effort at the top of the ticket. However, Brown’s almost assure victory could result in one of the lowest voter-turnouts in state history.
Among the House races, bids for the seats of retiring Reps. Buck McKeon, a Republican, and Henry Waxman,a Democrat, are expected to be among the most competitive.
The top-two vote-getters, regardless of their party, will advance to the general election, according to election laws revamped by voters in recent years.
Eighteen candidates are vying for Waxman’s Democratic-leaning 33rd-District seat that includes Malibu and Santa Monica.
Eight candidates, including four Republicans, are vying for McKeon’s seat, north of Los Angeles, which the nonpartisan Rothenberg Political Report rates as “lean Republican.”
Alabama has a gubernatorial, House and Senate race. Montana has a Senate and House race. New Jersey has one Senate and three House races. New Mexico has a governor and Senate race. And South Dakota has a governor and Senate race.
The Associated Press contributed to this report.