Sen. Bernie Sanders Bernie SandersButtigieg stands in as Pence for Harris's debate practice Bernie Sanders warns of 'nightmare scenario' if Trump refuses election results Harris joins women's voter mobilization event also featuring Pelosi, Gloria Steinem, Jane Fonda MORE (I-Vt.) on Tuesday said that his newly announced 2020 campaign for president would launch an "unprecedented" grass-roots movement that will help transform the U.S. economy and politics in the nation.

In an interview with "CBS This Morning," Sanders said that the biggest difference between his 2020 campaign and an unsuccessful for the Democratic nomination in 2016 was that "we're gonna win."

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"We're gonna win. We are gonna also launch what I think is unprecedented in modern American history and that is a grass-roots movement ... that will lay the groundwork for transforming the economic and political life of this country," Sanders said.

Sanders called defeating President Trump Donald John TrumpOmar fires back at Trump over rally remarks: 'This is my country' Pelosi: Trump hurrying to fill SCOTUS seat so he can repeal ObamaCare Trump mocks Biden appearance, mask use ahead of first debate MORE in 2020 the most important goal for Democrats.

“It is absolutely imperative that Donald Trump be defeated, because I think it is unacceptable and un-American, to be frank with you, that we have a president who is a pathological liar ... it gives me no pleasure to say that, but it's true," Sanders said.

Questioned by John Dickerson whether his values would be more in line with the Democratic base in 2020, Sanders noted that much of his 2016 presidential platform has become mainstream in the Democratic Party.

"I think a lot of people would say that," Sanders said.

Sanders also took shots at former Starbucks CEO Howard Schultz, accusing the possible 2020 candidate of trying to "blackmail" the Democratic Party by threatening to run as an independent if the party does not select a centrist as its nominee.

“There are a lot of people I know personally who work hard for a living, who make $40,000, $50,000 a year who know a lot more about politics than, in all due respect, does [Howard] Schultz," Sanders said.

"I think his deeper theory is, 'Hey, I'm a billionaire. Leave me alone. And let me make as much as money as I can without paying my fair share of taxes,' " the senator added.

Sanders placed second in the 2016 Democratic contest, and supported Hillary Clinton Hillary Diane Rodham ClintonButtigieg stands in as Pence for Harris's debate practice Senate GOP sees early Supreme Court vote as political booster shot Poll: 51 percent of voters want to abolish the electoral college MORE in the general election after endorsing her presidential campaign at the Democratic convention. If elected, he would be America's first Jewish president as well as the oldest person ever elected to a first term in the White House.