Not giving up. Bernie Sanders urged people to stand up against President-elect Donald Trump during a Monday, November 14, appearance on The Late Show. Watch what he said in the clip above.

The 75-year-old Vermont senator — who previously ran against Hillary Clinton for the Democratic presidential nomination, but later endorsed her — shared his take on the former secretary of state’s shocking loss to Trump, 70, in this year’s election.

“The [Democratic] party has got to transform itself to be a party which, first of all, opens the door — that is, the party that feels the pain of working-class people, of the middle class, of low-income people, of young people … that brings people into the party,” Sanders said, adding that the party cannot continue to be run “by the liberal elites.”

While the Our Revolution: Our Future to Believe In author told show host Stephen Colbert that he is not a “liberal elite,” he did say that they are “good, well-meaning people — they’re not my enemies, they’re partners of ours.”

Even though the Democratic party was defeated by the GOP in the 2016 race for the Oval Office — Republicans also won the Senate and House majorities — Sanders feels confident in saying that most Americans do not agree with some of Trump’s controversial views.

“Please do not think that all of the people who voted for Donald Trump agree with his sentiments about women or African Americans, or his rejection of the science regarding climate change,” Sanders said of the ex–Celebrity Apprentice host’s campaign, which he described as laden with “bigotry.” “They don’t. But for a variety of reasons, they did end up voting for [Trump].”

The politician added: “Our job now — in my view — is to figure out how we create an effective opposition. Now the truth is Democrats should not be losing to a candidate who insults so many people, who wants to give huge tax breaks to the top two-tenths of 1 percent and who rejects climate change. How are we losing these elections? Something is fundamentally wrong.”

“On virtually every issue I talk about … the vast majority of the American people are on our side. Trump’s views are a minority,” Sanders continued. “People do not think we should give tax breaks to billionaires. They do believe we should raise the minimum wage and have pay equity for women. They do believe we should make public colleges and universities tuition free.”

Sanders then went on to tell Colbert, 52, and his viewers that they need to take action if they want to make a difference. “So our job, right now, and this is terribly important at this moment ... What you do now is get heavily involved in the political process,” he said. “When millions of people stand up and fight back, we will not be denied.”

Watch the video above.  

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