US Democratic presidential candidate Hillary Clinton has beat her rival, Vermont senator Bernie Sanders in the primary contests in New Jersey and New Mexico, two of six states holding contests on Tuesday local time.

That also includes North Dakota where Sanders is projected to win. The polls in California has closed, but news networks said the race was too close to call. And there are no immediate projections in Montana or South Dakota. Her wins came a day after she secured enough superdelegates to become the Democratic presumptive presidential nominee.

Clinton has called this a "historic moment for women", as she is the first woman to lead a major party in a race for the White House.

Meanwhile, Donald Trump has won Republican primaries in Montana, News Mexico and South Dakota.