Newly announced Democratic presidential candidate Sen. Bernie Sanders has raised $6 million since his campaign launched Tuesday morning, and $5.9 million in the first 24 hours, Sanders' campaign tells CBS News' Jenna Gibson.

The Vermont senator's campaign raised $1 million from people in all 50 states in less than four hours after Sanders announced his bid. Sanders, appearing on "CBS This Morning," said he intends to win the Democratic nomination this time around. Sanders, now 77, lost to Hillary Clinton in the 2016 race for the Democratic nomination.

"We're gonna win," Sanders told "CBS This Morning" co-host John Dickerson.

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Sanders' initial fundraising haul appears to put him ahead of his competition. Last month, California's Sen. Kamala Harris raised roughly $1.5 million in the first 24 hours from all 50 states, which raised eyebrows at the time.

Sanders, who has described himself as a democratic socialist, said it's "absolutely imperative" that Democrats defeat Mr. Trump in 2020.

"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 on "CBS This Morning."

Sanders is pushing policies including Medicare for All and college for all, issues that are sure to come up in Democratic primary debates.

Sanders joins an already crowded field that includes Harris, Sens. Cory Booker, Elizabeth Warren, Kirsten Gillibrand, Rep. Tulsi Gabbard, Rep. Julian Castro, and others.