(CNN) We have less than a month until the primary season, and it's becoming more apparent that former Vice President Joe Biden and Sen. Bernie Sanders of Vermont are the candidates to beat. It's not just that they are Nos. 1 and 2 in the national polling. It's that each holds a lead on the two most important metrics beyond the polling: fundraising and endorsements.

Sanders reportedly pulled in about $34.5 million in the fourth quarter of 2019, which makes for a total sum of nearly $100 million over the 2020 campaign. No one else is even close. His nearest competitor (former South Bend, Indiana, Mayor Pete Buttigieg) is closer to $75 million for the year, according to self-reports.

Those who lead in fundraising at this point often win. In primaries in which an incumbent is not running in the given primary, 9 of 14 leaders at this point have gone on to win the nomination. Even when a candidate is trailing in the national polls (like Sanders), the leader has won 3 out of 5 times. This includes candidates like Democrat Bill Clinton in 1992 and Republican Mitt Romney in 2012.

Biden's fundraising is not anywhere near as strong as Sanders'. He took in $22.7 million this past quarter and about $60 million in the primary so far.

Biden, though, does significantly better in endorsements. He has 33 endorsements from members of Congress and governors. He scored his latest endorsement from Rep. Abby Finkenauer of Iowa this week, and he's the only candidate to get a congressional or gubernatorial endorsement in the last month. His closest competitor (Sen. Cory Booker of New Jersey) has only 13 endorsements. Sanders has a mere six.

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