After months of speculation, Vermont independent Senator Bernie Sanders announced he will run in the 2020 presidential election. This is Senator Sanders speaking to John Dickerson on ”CBS This Morning.”

Sen. Bernie Sanders: “I am going to run for president. That’s correct.”

John Dickerson: “What’s going to be different this time?”

Sen. Bernie Sanders: “We’re going to win. We are going to also launch what I think is unprecedented in modern American history, and that is a grassroots movement, John, to lay the groundwork for transforming the economic and political life of this country. That’s what’s different.”

Senator Sanders sought the nomination in 2016 but lost out to Hillary Clinton. Sanders has long been one of the most progressive voices in U.S. politics and promised to rein in corporate and Wall Street greed, while implementing social welfare programs like Medicare for all and free public college. In a 2015 presidential debate, Sanders declared climate change to be the greatest threat to national security. The Sanders campaign was credited for pushing Clinton’s rhetoric and policy positions further to the left.

Despite the Democratic Party establishment heavily favoring Clinton, Sanders carried primary races or caucuses in 23 out of 57 contests. Many accused Democrats of rigging the primary against Sanders, pointing to the Democratic National Committee’s apparent coordination and joint fundraising with the Clinton campaign. Leaked emails from the DNC also revealed tactics to paint Sanders in an unfavorable light.

Sanders joins a crowded field of Democratic hopefuls, including fellow Senators Elizabeth Warren, Cory Booker, Amy Klobuchar and Kamala Harris, as well as Congressmember Tulsi Gabbard, who endorsed Sanders in 2016.