Primary primer

There's an open governor's race in Maine; in New Jersey, it'll be worth watching to see if former Philadelphia Eagles player Jon Runyan wins the Republican nomination to face freshman Rep. John Adler (D-N.J.). Runyan is the party favorite but has been struggling.

8:30 p.m. EST: Arkansas

It's the biggest race of the night. Will Sen. Blanche Lincoln (D-Ark.) become the next lawmaker to fall to anti-incumbent fever? Unions have spent more than $65 million to help Lt. Gov. Bill Halter (D-Ark.) take her down, and the Democratic establishment has thrown its weight behind Lincoln.

9 p.m. EST:  North Dakota and South Dakota

Sen. Byron Dorgan (D-N.D.) is retiring but the primary races to replace him are not competitive.

10 p.m. EST: Iowa, Montana and Nevada

The second biggest race of the night is in Nevada, where both parties will wait to see who'll face Senate Majority Leader Harry Reid (D-Nev.) in November. Sue Lowden is the Republican Party favorite but she's recently come under heavy fire and Tea Party candidate Sharron Angle has pulled ahead in the polls. A Mason-Dixon poll released Sunday had Angle up by eight points and Lowden finishing third. Reid looked vulnerable earlier this year but his poll numbers have been slowly improving — perhaps thanks to all the GOP infighting during the primary campaign.

And it's worth keeping an eye on the Republican gubernatorial primary for the personalities involved. Republican Gov. Jim Gibbons went through a very nasty public divorce and was down 14 points in Sunday's Mason-Dixon poll.

11 p.m. EST: California

Three Republicans are fighting to take on Sen. Barbara Boxer (D-Calif.) A Survey USA poll released Tuesday had former Hewlett-Packard CEO Carly Fiorina up by 26 points. Fiorina has invested millions from her personal fortune into her campaign.

There's also a competitive primary for the GOP gubernatorial nomination, but it's often overlooked by the more-competitive Senate race. Between the two of them, former eBay CEO Meg Whitman and state insurance commissioner Steve Poizner have sunk at least $100 million of their own money in the race. It's a lot of money to pay for the right to face the Democratic nominee, Attorney General Jerry Brown, who served as governor in the '70s and '80s. A Survey USA poll Tuesday had Whitman up by 29 points.