Democratic United States presidential hopeful Barack Obama's momentum-driven campaign shows no signs of slowing down as he trounced party rival Hillary Clinton in the caucuses of Nebraska, Washington and Louisiana in the race for the nomination for the White House.

Obama, aiming to become the first black US president in history, garnered roughly twice the votes received by Hillary in Nebraska and Washington, which have 24 and 78 delegates respectively who will go to the Democratic National Convention to elect the party's nominee for the presidential election.

Obama also won comfortably in Louisiana, which has 56 delegates. With one-thirds of precincts counted, Obama has gained 53 per cent of the vote, compared to 38 per cent for Hillary, who is also seeking to script history by becoming the first woman president of the US, reports said.

The wins in Nebraska and Washington mean that Obama has won nine out of the ten Democratic caucuses with the exception of Nevada.

The final delegate count is still being tallied after Saturday night's showdown, but as of Friday, Clinton has a total of 1,055 delegates as opposed to Obama's 998. A total of 2,025 is required to win the democratic nomination.

All eyes will be on the 'Beltway Primaries', where Maryland, Virginia and Washington DC will have their political event next Tuesday where 175 delegates are at stake.

On March 4, Clinton and Obama will have their major showdown in Texas, Ohio, Rhode Island and Vermont where 370 delegates are at stake.