It's another step forward on the way to the November mid-term elections in the Congress for 2014, as voters in five states - Maine, North Dakota, Nevada, South Carolina and Virginia - go to the polls to choose candidates for U.S. House and Senate races.

Let's take a quick run around the country to see what's at stake, with the November elections now less than five months away.

1. Sen. Lindsey Graham tries to avoid runoff

For months, GOP opponents of Republican Lindsey Graham (R-SC) talked of how they would defeat the South Carolina Senator, who was first elected in 2002. Graham was blasted for his calls for immigration reform, and for not being conservative enough on a host of issues. So far, though, Graham seems to have righted the ship and isn't truly on Upset Alert in the Palmetto State. One way for Graham to make sure of that is to get more than 50 percent of the vote to avoid a runoff on June 24.

2. GOP Establishment vs Tea Party

One of the more intriguing races to watch tonight is in Virginia, where House Majority Leader Eric Cantor (R-VA) has been on the attack against his primary foe for weeks.

Cantor has a huge financial advantage - and organizational - over challenger David Brat. Even though Cantor's forces stumbled recently when his choice for party chair in his Congressional district was defeated by opponents this spring, Cantor's backers seem confident they will win easy on Tuesday, in what is one of the two GOP Establishment vs Tea Party type races on this primary day.

3. Only a few primaries for sitting lawmakers

If you want to watch election results that will bring down members of Congress who are running for re-election, tonight might not be the night. No members have a primary in either Maine or North Dakota, two of four have a primary in Nevada, two of seven in South Carolina and two of nine in Virginia. The next round of primaries is in two weeks on June 24 in Colorado, Maryland, Oklahoma, New York and Utah; plus we will have runoffs in Mississippi (and maybe South Carolina).

4. Not all primaries are created equal

Virginia is a good example of how every state can do things a bit differently when it comes to elections for the Congress. In this primary, you won't find one Democrat on the ballot for any U.S. House seats - because Democrats decided to pick their nominees by conventions in local Congressional districts. Republicans have chosen some of their nominees already, and tonight only have two primaries; one of their party nominees was chosen a few weeks back in a "firehouse primary" where voters showed up on a Saturday to vote at certain fire stations around the district. So yes, it is primary day in Virginia, but not for everyone.