The Hill reported on Sunday that Bernie Sanders is considering a 2020 presidential run. When asked if the Vermont senator was keeping the door open for another go at the presidency, an unnamed associate of Sanders replied that "yes is the answer," according to The Hill. That same associate suggested that Sanders doesn't want Joe Biden to win the Democratic nomination, should the former vice president seek it.

"[Sanders] thinks he's earned the right to run again and he believes if he would have been the [Democratic] candidate, he would have won against Trump," the source told the Hill. "The last thing he's going to do is step aside and let Joe Biden take it."

Jeff Weaver, a longtime advisor to Sanders, also confirmed that the 2016 Democratic primary candidate is "keeping the door open" to a 2020 presidential run, according to The Hill. Sanders himself refused to rule out a 2020 run earlier in July.

Although Sanders is a registered independent and identifies as a democratic socialist, he caucuses with the Democrats in the Senate, and ran for the Democratic Party nomination in 2016. Larry Cohen, a former adviser to the senator, predicted that Sanders will run as a Democrat if he does take the plunge in 2020.

Sanders is a controversial figure within the broader American left, and as such, progressives are starkly divided on the question of whether or not a Sanders 2020 run is a good idea.

Daily Kos founder Markos Moulitsas told POLITICO Sanders is a "constant reminder" of the divide within the left, and said that his continued presence and visibility within the Democratic Party "allows the healing that needs to take place to not take place." Others have cited his age (Sanders would be 79 on election day), moderate positions on certain policy issues (most notably gun control), and difficulty attracting voters of color as reasons why he should stay on the sidelines in 2020.

Biden is often mentioned as a possible Democratic presidential candidate in 2020, and he's indicated on several occasions that he's not ruling out the possibility. The former Senate colleagues have spoken fondly of one another on a personal level, but in 2015, Sanders said that Biden represents "conventional establishment politics," a stark contrast to Sanders' revolutionary brand of leftism. A July poll found that both Biden and Sanders would likely defeat President Trump in a head-to-head matchup.

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According to an April poll, Sanders is the most popular politician in the country, Democrat or Republican. He remains the most vocal (and perhaps only) advocate in the Democratic Party for aggressively leftist economic policies and non-interventionism on the foreign stage, and so far, nobody else in the party has attempted to claim this mantle. The Democratic National Committee badly wants to get its hands on Sanders' mailing list, and it's not a surprise why — he simply commands a huge following among people who might vote Democrat in 2020.

Sanders has been very active since the 2016 election. After barnstorming red states in a "unity tour" with DNC Chair Tom Perez, the Vermont senator held campaign-style rallies in West Virginia and Kentucky to mobilize support against the Republican health care bill. Earlier in July, he spoke at an event in Iowa, whose caucuses are generally considered the kick-off of the presidential primary season.