The former presidential candidate has teamed up with the head of the Democratic National Committee, Tom Perez, for the eight-state tour, which kicked off in Maine on Monday.
Sanders lost to Hillary Clinton, who later became the Democratic nominee for president, by double digits in Arizona's presidential preference election in March of 2016. Sanders would later back Clinton in the general election against Republican Donald Trump, who became president.
The national tour's goal is to create a stronger Democratic party, especially with Congress and the Presidency in the hands of Republicans.
Sanders and Perez are expected to speak in support of raising the minimum wage to $15, equal pay for women, rebuilding infrastructure and battling climate change. They'll also focus on health care and the recent Republican health care proposal.
The pair made their first stop on the tour on Monday in Portland, Maine.
"Our job is to radically transform the Democratic party," Sanders told the crowd.
Sanders also announced he plans to introduce new Medicaid legislation.
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