Clinton secures enough delegates for Democratic nomination

Hillary Clinton has reached the number of delegates needed to clinch the US Democratic presidential nomination, the Associated Press said on Twitter on Monday.

Clinton called for party unity on Monday, suggesting it was time for Bernie Sanders to abandon his hard-fought challenge, as six states hold nominating contests on Tuesday when she expects to clinch the Democratic presidential nomination.

Clinton told reporters in California that Tuesday marked eight years from the day she withdrew from the 2008 White House race, endorsing Barack Obama after a bitter rivalry. Her supporters have said Sanders should look at that as a road map for his own exit from this year's race.

After staying above the campaign fray for months, Obama could endorse his former secretary of state as early as this week, the New York Times and CNN reported. White House press secretary Josh Earnest told reporters the president was waiting for New Jersey and California to vote on Tuesday before weighing in.

Tuesday's voting is expected to clinch the Democratic nomination for Clinton, 68, which would make her the first woman nominated for president by a major U.S. political party.

Her campaign hopes an expected victory in New Jersey will give her enough delegates to effectively lock up the nomination early in the evening, before the results come in from California, the biggest electoral prize and likely the last to report results on Tuesday.

An Obama endorsement would come as a welcome boost to Clinton and to Democrats concerned the party needs to turn its attention to campaigning against Trump. While he has made remarks indicating a preference for Clinton, Obama has so far avoided a clear endorsement.

Obama remains popular with many voters. His job approval was over 50 percent in a recent Reuters/Ipsos poll and has been on the rise in 2016.