Vermont Senator Bernie Sanders on Tuesday endorsed Democratic presidential candidate Hillary Clinton. He congratulated her for winning the Democratic nominating process and thanked the “13 million Americans” who voted for him in the primaries and caucuses across the country and helped with his presidential campaign. “She will be the Democratic nominee for president, and I intend to do everything I can to make certain that she will be the next president of the United States,” Sanders said, adding that he would make why she should be the next president clear, The New York Times reported.

Sanders appeared with Clinton at a campaign event in New Hampshire, where he defeated her in a primary in February. Clinton was dubbed the presumptive Democratic presidential nominee early in June, when she had the overall support of the required 2,383 delegates to secure the nomination.

The official announcement of his support for Clinton comes after he earlier said that he will vote for her in the presidential election in November. He had also pledged to help Democrats from stopping controversial Republican nominee Donald Trump from reaching the Oval Office.