6 tidbits on 8 primary states

As voters go to the polls in eight different states, a variety of races for the Congress may keep political animals up late on Tuesday, as a senior Republican Senator's fight for primary survival headlines this latest mid-term Tuesday in 2014.

Primaries are on tap today in Alabama, California, Iowa, Mississippi, Montana, New Jersey, New Mexico and South Dakota - let's review some of what's at stake:

1. Mississippi Senate Brawl

The re-election bid of Sen. Thad Cochran (R-MS) has become an all-out GOP primary brawl, as Tea Party candidate Chris McDaniel has aggressively challenged Cochran, who was first elected back in 1978. A poll out last week had Cochran leading by 5 points, but below 50 percent. For many outside conservative groups, a McDaniel win is something they are desperately hoping for, as the GOP Establishment has done very well so far in 2014. There are runoff elections in Mississippi, so with three candidates in the GOP race, it isn't out of the question that this race could go into overtime for another three weeks until the runoff on June 24.

2. California Top-Two

California's 53 U.S. House seats are once again being contested under the 'top two' primary, where candidates from all different parties (and 'No Party Preference) are lumped into one race, and then the top two finishers advance to November. In some districts, the final two candidates will both be Democrats, in others they could both be Republican. Maybe the most active race is in the 33rd district, where over a dozen candidates of all stripes are on the ballot to succeed Rep. Henry Waxman (D-CA). The most expensive race may be in the 17th district, where Rep. Mike Honda (D-CA) has raised over $2 million, but so has one of his opponents, Ro Khanna. With a four candidate field, those two could face off again in November.

3. One Third of U.S. House incumbents rest easy

Of the 75 incumbents running for re-election in the U.S. House today, 25 of them have a free ride to the November election. Most of the action - logically - is in California, where 32 of the 47 incumbents bidding for another term have drawn opposition in California's 'top two' primary system. New Jersey is the next busiest state, with five of 11 sitting House members facing a primary opponent. Meanwhile, Rep. Robert Aderholt (R-AL) not only has no primary opponent, but no one on the ballot against him in November, while Kevin McCarthy (R-CA) has only write-in opposition in November, the same for Rep. Janice Hahn (D-CA).

4. Four lawmakers seek political comeback

In two totally different states, California and Mississippi, a pair of ex-members of the U.S. House are trying to return to Washington for another chapter. In the Golden State, ex-Rep. Doug Ose (R-CA), who served three terms between 1998 and 2004, is trying for a comeback in the 7th district, while ex-Rep. Joe Baca (D-CA) - who lost two years ago - is back for another run in the 31st district. In the Magnolia State, ex-Rep. Travis Childers (D-MS) is bidding for U.S. Senate (he'll face the Cochran-McDaniel winner) and ex-Rep. Gene Taylor (D-MS) has now switched parties, and is running against Rep. Steve Palazzo (R-MS), who defeated Taylor in 2010.

5. Runoffs and Conventions

As usual, the rules make a difference in each state, and we have some variety tonight. Alabama has a 50% rule for runoffs - get over 50% and you win outright; Mississippi has the same primary runoff rule as well. In South Dakota, if no one gets to 35% in races for U.S. House, U.S. Senate or Governor, then there is a runoff that is officially called a 'secondary' election. Iowa also has a 35% rule for primaries in the Hawkeye State - but if no one gets to that threshold, then the battle is settled at the state party convention, not in a runoff. That could be a possibility in the crowded Iowa race for the Republican nomination for U.S. Senate.

6. The Battle for Senate in Iowa

With Sen. Tom Harkin (D-IA) not running for another term, Republicans have tried to rally behind state Senator Joni Ernst, and make sure that race does not go to a state convention to choose a GOP nominee. The candidate of choice for many in both the GOP Establishment and for outside groups has been Ernst; she's been endorsed by Sarah Palin, by Mitt Romney, by Marco Rubio, the U.S. Chamber of Commerce, the Senate Conservatives Fund and more. In other states, the GOP factions have fought each other, but not so much in the Hawkeye State, where Ernst has had a strong lead in recent polls.