U.S. Democratic presidential candidate Barack Obama prevailed in all of the four primaries and caucuses on Saturday, a big boost to his campaign to gain the edge in the presidential nominating races.

Republican No. 2, Mike Huckabee also swept the three primaries and caucuses in the first round of the post-Super Tuesday races, and only had two percentage points in the Washington caucuses behind his rival, John McCain.

Speaking to a cheering audience of Democrats at a party dinner in Virginia, Obama showed his confidence in winning the state.

Today the voters from the West Coast to the Gulf Coast to the heart of America stood up to say, 'yes we can'. We won in Louisiana. We won in Nebraska. We won in Washington State. We won north, we won south, we won in-between. And I believe that we can win Virginia on Tuesday if you're ready to stand for change.

On Sunday, Obama and Clinton will compete in caucuses in Maine, vying for the 24 delegates. Following the weekend contests, Clinton and Obama will continue their race Tuesday in Virginia, Maryland and Washington D.C., where Huckabee and McCain, the two Republican candidates, will also compete on the same day.

On March 4, voting will take place for the candidates in Ohio, Texas, Rhod Island and Vermont.