(For a full list of candidates, see the Delaware [3], District of Columbia [4], Minnesota [5], New Hampshire [6], New York [7], Rhode Island [8], Vermont [9] and Wisconsin [10] portals.)

By Congresspedia assistant editor Avelino Maestas [11]

It’s almost like Super Tuesday again: seven states and the District of Columbia are holding primary elections today. The races in some states are perfunctory, with little or no opposition for incumbents, while other districts are hotly contested. Either way, today's races will set up some of the most important match-ups in November, and our citizen-journalists have been tracking them on Congresspedia [12].

Delaware [3]
Vice-presidential candidate Joe Biden [13] is up for re-election this year. There are no other Democrats challenging him for the Senate seat, and Republican Christine O'Donnell [14] is also unopposed. Meanwhile, two Democrats are battling for the chance to challenge at-large Rep. Mike Castle [15] (R).

District of Columbia [4]
In 1982, in a bid for statehood, District residents approved what would have been a state constitution, and called for the election of a shadow representative and two shadow senators, who would assume office in Congress if statehood was granted.

Residents continue to elect shadow senators and a shadow representative (in addition to the non-voting delegate. Rep. Eleanor Holmes Norton [16] (D), the delegate, is unopposed today, as is shadow representative Mike Panetta [17] (D). Incumbent shadow senator Paul Strauss [18], a Democrat, is being challenged by Philip Pannell [19] in today’s primary.

Click through for previews of primaries in the other states.

Minnesota [5]
The big news in Minnesota is the senate race. Earlier this year, actor and comedian Al Franken [20] received the endorsement of the state party, and he’ll likely win the Democratic nomination today. He is forcing a tough challenge of Sen. Norm Coleman [21] (R), who has one opponent — Jack Shepard [22] — in today’s primary.

There’s also an open House seat due to the pending retirement of Rep. Jim Ramstad [23] (R) in CD-03. The Democratic and Republican candidates, however, are unopposed in their respective primaries.

New Hampshire [6]
The Senate race seems to be all decided: incumbent Sen. John Sununu [24] (R) has minor opposition, as does Democratic front-runner Jeane Shaheen [25]. There are several GOP candidates trying to challenge Rep. Carol Shea-Porter [26] (D) in the 1st congressional district, including Jeb Bradley [27], Geoff Michael [28] and John Stephen [29]. The field is even larger in CD-02, where five Republicans are vying for a spot on the November ballot. Rep. Paul Hodes [30] (D) is unopposed.

New York [7]
Neither Senate seat is up for election this year in New York, but there are a number of interesting races. Outsides are probably familiar with the case of Rep. Vito Fossella [31] (R), the 13th district congressman who announced he would not seek re-election following his driving while intoxicated arrest in May. Both parties have contested races in the district’s primary today, and it is probably the best chance New York Democrats have of flipping a seat this cycle.

In the 21st congressional district, Rep. Mike McNulty [32] has decided to retire following the 110th Congress. A whole bunch of Democrats (7!) are trying for the chance to replace him, as are several Republicans.

Rhode Island [8]
Sen. Jack Reed [33] (D) is running for re-election this year, and while two other Democrats (Vernon Craig [34] and Chris Young [35]) are challenging him, Reed should win easily. The state’s incumbent House members, Reps. Patrick Kennedy [36] (D) and James Langevin [37] (D) are unopposed.

Wisconsin [10]
A trio of Democrats are on the ballot in the 1st district, where Rep. Paul Ryan [38] (R) is unopposed today. Paulette Garin [39], Marge Krupp [40] and John Mogk [41] will battle it out for the Democratic nomination. Other races in the state appear to be set.

As part of our Wiki the Vote [42] project, our citizen-editors have been tracking all the races and building profiles of many of the candidates. We’ll have more on the winners Wednesday (including the challengers' occupations), so stay tuned then. In the meantime, if you know something about any of the races listed above, or any race in the country, please post it for your fellow citizens to read: Find your state at the Wiki The Vote homepage [43], select a candidate or incumbent and click "edit." It’s easy, and you can always ask one of our staff editors [44] for help.