House Majority Whip James Clyburn, D-S.C., was expected to announce Tuesday -- the last day of the Democratic primary season -- his endorsement of Obama, CNN reported.
Meanwhile, several uncommitted congressional Democrats discussed how and when to announce their support for Obama, several media sources reported.
Most of the uncommitted lawmakers will endorse Obama this week, sources told CNN. A group of eight legislators is prepared to announce its support of Obama as soon as the polls close in South Dakota, The New York Times reported.
"I think most people realize this process is coming to an end, and it's important to bring this matter to a conclusion," Sen. Ben Cardin, D-Md., told CNN. "I've said my support would be for the person who had the most support, without any specific formula, in the primaries and caucuses, and had the momentum going into the general election and has our best chance of winning in November."
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