Sen. Bernie Sanders, independent of Vermont, announced Tuesday he is launching a bid for the 2020 Democratic presidential nomination, hoping to reignite the ardent progressive support of his insurgent 2016 campaign.

“We’re gonna win,” Sanders told “CBS This Morning” co-host John Dickerson. In his second run, Sanders is vowing to launch a grassroots movement that will “lay the groundwork for transforming the economic and political life of this country.”

He stressed that the chief priority for Democrats is to thwart President Trump’s reelection bid next year. “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,” Sanders said during a wide-ranging interview in his home in Vermont.

“We have a president who is a racist, who is a sexist, who is a xenophobe, who is doing what no president in our lifetimes has come close to do doing, and that is trying to divide us up,” he added.

By joining the most diverse Democratic primary field in U.S. history, the 77-year-old self-described democratic socialist will face more difficulty billing himself as the standard-bearer of the Democratic Party’s progressive wing this time around. In 2016, Sanders mounted a forceful but ultimately unsuccessful challengeagainst establishment candidate and eventual Democratic nominee Hillary Clinton, prompting her to move to the left on several key issues.

But the three-term senator is now entering a field already crowded with several high-profile candidates — including five other senators — but no clear favorite. Candidates like Sen. Elizabeth Warren of Massachusetts have already begun highlighting their progressive bona fides on the campaign trail, throwing their support behind bold proposals like Medicare for All and the Green New Deal while touting a tough stance on Wall Street.

So far, nearly a dozen Democrats have declared their candidacy for president or launched presidential exploratory committees, including senators Warren, Kirsten Gillibrand, Kamala Harris, Cory Booker and Amy Klobuchar; Hawaii Rep. Tulsi Gabbard; and former Housing and Urban Development (HUD) secretary Julián Castro. Several others, like former Vice President Joe Biden, former Texas Rep. Beto O’Rourke, Sen. Sherrod Brown of Ohio and former New York City mayor Michael Bloomberg, are also mulling bids for the Democratic nomination.

Sanders said he will again campaign on progressive policies like raising the minimum wage, universal healthcare and tuition-free public higher education, making them fundamental issues of his second White House bid. The Vermont lawmaker took credit for the support that these policies, once considered fringe proposals, have garnered among rank-and-file Democrats.

“All of those ideas people were saying, ‘Oh Bernie, they’re so radical. They are extreme. The American people just won’t accept those ideas.’ Well, you know what’s happened in over three years? All of those ideas and many more are now part of the political mainstream,” he said.

Dickerson also asked Sanders about former Starbucks CEO Howard Schultz, who has said he’s mulling an independent White House run but might drop it if Democrats choose a moderate, rather than a progressive, to take on Donald Trump. Sanders dismissed Schultz as a billionaire who’s essentially “blackmailing the Democratic Party.”

“If you don’t nominate Bernie Sanders he’s not gonna run?” Sanders said of Schultz. “Well, I don’t think we should succumb to that kind of blackmail.”

Dickerson pointed out that Schultz represents the argument that Democrats, in order to win voters in more conservative parts of the country, have to pick a candidate who isn’t as radical.

“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,'” Sanders countered, without acknowledging the point.

In the 2020 campaign cycle, Sanders can expect to confront some of the same hurdles that hindered his 2016 campaign, including his struggle to galvanize minority voters and his insistence on identifying as an independent and not as a Democrat.

Sanders garnered more than 13 million primary votes and carried 23 states during the Democratic primaries by energizing a movement of young voters with his fiery populist rhetoric. But he consistently underperformed among African-American and Latino voters and suffered humbling defeats to Clinton in diverse states, like California and South Carolina.

After Mr. Trump’s stunning victory two years ago, many Democrats, including Clinton herself, criticized Sanders for what they believed was his tepid support for Clinton, and for the tenor of his primary campaign. In her book What Happened,Clinton wrote of Sanders, “His attacks caused lasting damage, making it harder to unify progressives in the general election and paving the way for Trump’s ‘Crooked Hillary’ campaign.”

During the interview with CBS News, Sanders downplayed the criticism he has received for not running as a Democrat in Congress, saying he’s caucused with congressional Democrats for decades. But he added that a growing number of Americans are dissatisfied with both Republicans and Democrats.

“If the Democratic party is going to do well in the future, I think they have to reach out to those independents, including, by the way, a lot of young people, a lot of people of color, and bring them into the Democratic Party. And I think I’m in a good position to do that,” he said.

Recently, Sanders has also been forced to address allegations from several female staff members of his 2016 campaign who say they were harassed. In a public apology last month, he denounced sexism and said the women’s experiences were not part of “what a progressive campaign, or any campaign, should be about.”

Sanders has also met with some of the women from his 2016 campaign who said they experienced harassment and felt discriminated against. Dickerson asked him what he learned from them.

“I learned that that was true. And, it … breaks my heart,” he said. His campaign, Sanders recalled, “kind of exploded,” rapidly expanding from “a few” to “a lot” of staffers. “And I will be very honest in telling you that, in retrospect, some of the people that were hired should not have been hired, and some women went through experiences that they should not have,” he told Dickerson.

“This has been an issue that has upset me and we’re gonna rectify it in this campaign,” Sanders said, pledging to implement the “strongest protocols” to protect women and other staff members working in his new campaign from harassment.

Since Mr. Trump’s election, the Vermont senator has joined his Democratic colleagues in opposing most of the president’s Cabinet and Supreme Court nominees and his policies on immigration, climate change and the tax system. Sanders has called the president a “pathological liar” and vowed to defeat “Trumpism and the Republican right-wing ideology.”

In 2017, his “Medicare for All” legislation was backed by 16 Senate Democrats, including most of the ones who have launched White House bids. Sanders, who has been outspoken in his criticism of U.S. military interventions abroad and has advocated for defense cuts, spearheaded a resolution to end U.S. support for the Saudi-led coalition waging a bloody war in Yemen that passed in the Senate in December.

Before his election to the Senate in 2006, Sanders represented Vermont’s at-large congressional district in the House for 16 years. He has made universal healthcare, tuition-free college education and efforts to combat income inequality integral themes of his legislative agenda. Sanders also opposed the 1991 and 2002 resolutions to authorize military engagement in Iraq.

Prior to his tenure in Congress, Sanders served as mayor of Burlington, Vermont for three terms. As a politically active college student at the University of Chicago during the 1960s, he was involved in the civil rights movement.

Sanders, the son of Jewish immigrants from eastern Europe, was born and raised in Brooklyn. Reports cbsnews