Senate up for grabs: here's the list

For shits, giggles, my own edification and convenience, I decided to spend a primary evening assembling a list of what we know about the November races that matter almost as much as the presidential contest. These Senate races that will determine which party controls the chamber and hence nominations of Supreme Court justices. At present, the Republicans have a 54-46 margin there. Democrats need at least four pickups (and a Dem vice president to break ties) for a winning margin.

This is possible, though not easy. There is considerable electoral history which suggests that Senate races, though they take place in very different states, tend to break similarly across the country in any particular year. (The only time I worked in a Senate race, Vermont 1970, we got swept up in such a debacle and lost anti-Vietnam war Democratic senators across the country.) This could be a promising year for a very strong Democratic showing depending how much of an additional mess the GOP makes of its presidential race

There are a few places where Democrats have to hold on to contested seats in contests that could make winning a majority harder.

• Nevada: That unpopular political wizard Senate Minority Leader Harry Reid is retiring. He looks to have cleared the field for a former state attorney general, Catherine Cortez Masto. The state has been voting Democratic in presidential elections, but also currently has elected a Republican governor, so it could swing either way. This one is no shoo-in.

• Colorado: Democratic incumbent Michael Bennet could be endangered if this battleground state went to the Republican presidential nominee -- but it probably won't.

Then there are several states where Democrats have a good chance to pick up a seat.

• Wisconsin: This state voted by 53% for Obama in 2012, elected a lesbian Democratic senator the same year -- and keeps returning Mr. Union Buster Republican Scott Walker as governor in off years. Go figure. Former Democratic Senator Russ Feingold who lost his 2010 re-election bid is trying to take the seat back this year and has consistently led the Republican opponent in early polling. This one looks good unless Wisconsin swings away from the Dems in the presidential.

• Florida: Republican Senator Marco Rubio rolled the dice on winning the presidential nomination and announced he would not run for re-election. We will now see whether he keeps that promise as the filing deadline is not until early May. He seems pretty damaged goods. Two major Democratic candidates are fighting for that nomination in a late August primary: Congressman Patrick Murphy has the support of the Democratic establishment. Congressman Alan Grayson is running an anti-establishment campaign. During the Obamacare debate, he thrilled many of us by baldly pointing out that the Republican healthcare plan could be summarized as "Die Quickly." His Cayman Islands hedge funds have damped some of that enthusiasm. The Republican field is huge and split, also facing an August 30 primary. Florida will be a presidential battleground state; Obama won it twice, very narrowly. This one is genuinely unpredictable.

• Illinois: Republican Senator Mark Kirk currently holds the seat that once was Obama's. Congresswoman and Iraq vet Tammy Duckworth won her primary yesterday and she aims to win it back. Her chances look good.

Three Republican seats are in play that might be out of reach in a non-presidential year.

• New Hampshire: Popular Democratic governor Maggie Hassan aims to unseat Republican incumbent Kelly Ayotte. Obama won this state twice, but it is swingy down-ballot.

• Ohio: Former Democratic governor Ted Strickland won his primary yesterday. Obama won this state too, but again it is swingy down-ballot. Strickland faces Republican incumbent Rob Portman.

• Pennsylvania: Another state that usually votes Democratic for president, it nonetheless sometimes elects Republican senators. The incumbent, Pat Toomey, is no eastern moderate, but a former president of the big business lobby Club for Growth. The Democratic candidate will be decided in an April 26 primary between Joe Sestak who lost to Toomey in 2010 and a candidate from the state Democratic leadership, Katie McGinty.

Unexpected events could put additional Republican-held senate seats in play in North Carolina, Arizona, Indiana and Missouri, but that would take an exceptionally good showing from Democrats.

Winning a Democratic majority in the Senate looks to be a tough project. Most of us who don't live in these battlegrounds are reduced to serving as, at best, small donors, and mostly just as onlookers. The shape of the next few years depends almost as much on these contests as on the Presidential race.