SANTA MONICA, United States: Bernie Sanders refused to concede defeat to Hillary Clinton late Tuesday (Wednesday in Manila), vowing to “continue the fight” for the Democratic nomination despite his rival declaring herself the party’s flag-bearer for the US presidential race. “Next Tuesday we continue the fight in the last primary in Washington DC,” the senator from Vermont told supporters in California. “And then we take our fight for social, economic, racial and environmental justice to Philadelphia,” where the Democratic convention will be held to formally nominate the party’s candidate to challenge Republican Donald Trump for the White House. Sanders appeared to ignore the political writing on the wall, after Clinton surpassed the number of delegates necessary to clinch the party’s nomination. Tuesday was the last major date of the 2016 primary calendar, with six states voting. The former secretary of state extended her delegate lead with wins in New Jersey, New Mexico and South Dakota. Sanders won North Dakota and Montana, US networks said. The grand prize, California, had yet to be called, but Clinton was holding a substantial lead.