For other successful politicians, they are a winnowing process. That is the situation in Maryland, where Representative Ben Cardin and Kweisi Mfume, a former representative and one-time head of the NAACP, are the best known among 18 contenders for the Democratic Senate nomination.
The primary winner will run against Michael Steele, the state's lieutenant governor. If elected, Steele would be the Senate's only black Republican.
Republicans, facing the possibility of the loss of seats in several states, hope Steele can become their brightest star of the year, even though it has been more than a quarter-century since the GOP has won a Senate race in Maryland.
After Tuesday's primary, the Democratic nominee ``will be broke and without momentum facing a strong candidate with a message of empowerment that is resonating across Maryland," said Dan Ronayne, spokesman for the Republican senatorial committee.
For the political parties, the week's primaries represent another in a dwindling number of chances to influence the lineup for the November ballot, when the GOP's continued control of the House and the Senate is at stake. Hence, the controversy.
In a Tucson-area seat in Arizona, the National Republican Congressional Committee has run an ad supporting Steve Huffman, praising him as an advocate of lower taxes and a ``common sense approach to immigration that puts security first." Huffman is ``the conservative choice," said the commercial.
A recent poll showed Huffman trailing a former state lawmaker, Randy Graf .
Graf won 43 percent of the primary vote in an unsuccessful run against Representative Jim Kolbe two years ago, but party officials have expressed concerns he may be too conservative to win the seat in November.
The decision by strategists in Washington to intervene did not impress Graf or the three other contenders for the nomination. They held a news conference to criticize the move.
``They're idiots," said one, former state party chairman Mike Hellon. He and the three other Republicans running said the GOP had split the party and they predicted Democrats would benefit.