Democrat Barack Obama hopes to extend his winning streak over rival Hillary Clinton today when voters in three more states make their choices in the Democratic presidential race.
Mr Obama is favoured in Maryland, Virginia and Washington, DC, as he and Mrs Clinton battle for the 168 pledged convention delegates at stake in the voting.
He easily swept four weekend contests in the states of Maine, Louisiana, Nebraska and Washington.
Republican front-runner John McCain and former Arkansas governor Mike Huckabee square off in Virginia, Maryland and the District of Columbia as Mr McCain tries to move closer to clinching the party's nomination.
Mr McCain has built a nearly insurmountable lead in delegates to the nominating convention and became the likely nominee last week with the withdrawal of his top rival, former Massachusetts governor Mitt Romney.
Mr McCain has won more than 700 of the 1,191 delegates needed for nomination, while Mr Huckabee has barely more than 200.
Illinois senator Mr Obama has 943 pledged delegates to Mrs Clinton's 895, according to a count by MSNBC - well short of the 2,025 needed to clinch the Democratic nomination.