Washington, DC: Senator Bernie Sanders on Tuesday launched his second bid for the White House, taking direct aim at Donald Trump in an announcement that calls the US president a "pathological liar." Sanders, 77, joins an already crowded field of candidates seeking to win the Democratic nomination and take on President Donald Trump in 2020.

Sanders made the announcement in a radio interview with a station from his home state of Vermont. "I wanted to let the people of the state of Vermont know about this first," Sanders said on Vermont Public Radio.

The self-described Democratic socialist gave an outline Tuesday of how he will campaign. "What I promise to do is, as I go around the country, is to take the values that all of us in Vermont are proud of -- a belief in justice, in community, in grassroots politics, in town meetings -- that's what I'm going to carry all over this country," he said.

In a video announcing his candidacy, Sanders called Trump pathological liar and a racist.

"We are living in a pivotal and dangerous moment in American history. We are running against a president who is a pathological liar, a fraud, a racist, a sexist, a xenophobe and someone who is undermining American democracy as he leads us in an authoritarian direction," Sanders said. "Now more than ever, we need leadership that brings us together, not divides us up," he said.

Sanders also highlighted policies he will advocate on the campaign trail: healthcare for all, raising the minimum wage to a "living wage," and combatting climate change.

"Our campaign is about transforming our country and creating a government based on the principles of economic, social, racial and environmental justice," Sanders said.

"Our campaign is about taking on the powerful special interests that dominate our economic and political life," he said, naming Wall Street, health insurance companies and the military-industrial complex, among others.

Sanders, an independent who caucuses with Democrats, made an unsuccessful bid for the presidency in 2016, losing out to Hillary Clinton, who was in turn was defeated by Donald Trump.

Like Trump, Sanders was an outsider when the 2016 presidential primaries began, but he came close to pulling off an upset over Clinton. He garnered passionate support among young liberals with his calls for universal health care, a $15 minimum wage and free public university education.

In the video, Sanders said that policies he advocated during the 2016 campaign have made their way into the political mainstream, and that it is now time to "complete that revolution." "All of these policies and more are now supported by a majority of Americans.

Together you and I and our 2016 campaign began the political revolution. Now it is time to complete that revolution and implement the vision that we fought for," he said.

Sanders served in the House until 2006 when he was elected to the US Senate. He was re-elected in 2012 and 2018.