Once bitten, twice shy is the saying but it appears that saying does not exist in the dictionary of Senator Bernie Sanders.

He is taking a shot at the presidency once again.

The 77-year-old 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, joins an already crowded field of candidates seeking to win the Democratic nomination and take on President Donald Trump in 2020.

He made the announcement in a radio interview with a station from his home state of Vermont.

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“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.