Bernie's last stand against Biden in the 2020 race could be on March 17

• Sen. Bernie Sanders underperformed on Super Tuesday, raising questions about the strength of his 2020 campaign.
• Former Vice President Joe Biden won the day, and his victories propelled him to a lead in the delegate count.
• 1,991 is the number of pledged delegates needed to win the 2020 Democratic nomination, and there are still a lot of delegates on the table in upcoming contests. The race is far from over.
• But March 17 could really be a make or break day for Sanders. There are four primary contests and 577 delegates at stake in Arizona, Florida, Illinois, and Ohio.
• If Biden sweeps these states, there will likely be increasing pressure for Sanders to drop out.
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Sen. Bernie Sanders woke up yesterday the frontrunner for the 2020 Democratic nomination, expected to clean up in a number of Super Tuesday contests across the country. But he went to bed behind former Vice President Joe Biden in the delegate count, with grave questions about his path to the nomination.

Sanders' last stand in the 2020 race could be on March 17, when several delegate-rich, diverse states vote. If he doesn't win big in those states - Arizona, Florida, Illinois, and Ohio - then it will be extremely difficult for the self-declared democratic socialist to best Biden.

If Biden sweeps these states, there could be strong pressure for Sanders to drop out of the race. This would be true for any candidate, but especially for Sanders given he continues to face criticism for not dropping out earlier in 2016 - and Democrats want to ensure that the party is unified against President Donald Trump.

Winning the Democratic nomination for president is all about obtaining pledged delegates sent to the Democratic National Convention. When voters go to the polls in primaries, they're actually voting to send delegates to the presidential nominating convention in Milwaukee in July. Delegates are allocated proportionally per the outcome of the voting contests, but candidates have to earn 15% of the vote at either the state level or in a specific congressional or state legislative district to win any delegates at all.

With most results in as of Wednesday afternoon, it's safe to say Sanders won a solid victory in California, which had the most pledged delegates up for grabs (415). But Biden wiped the floor with the other candidates, including Sanders, in a slew of other contests - particularly in southern states like Alabama and Arkansas. The former vice president came away with a sizable lead in pledged delegates (492), with Sanders trailing by roughly 60 (430), according to Decision Desk HQ.

The current breakdown of delegates does not mean Biden has clinched the Democratic nomination. 1,991 is the magic number of pledged delegates needed to win (it's a simple majority out of 3,979 total pledged delegates), and there are still dozens of voting contests left across the country.

On March 17, which happens to be St. Patrick's Day, there are collectively 577 delegates on the table in four Democratic primaries (nearly 15% of all pledged delegates sent to the Democratic National Convention):

• Arizona: 67 pledged delegates
• Florida: 219 pledged delegates
• Illinois: 155 pledged delegates
• Ohio: 136 pledged delegates

The race is increasingly shaping up to be a showdown between Sanders and Bernie. Several candidates have dropped out in the past few days, including billionaire Mike Bloomberg, Sen. Amy Klobuchar of Minnesota, and former South Bend Mayor Pete Buttigieg. Sen. Elizabeth Warren of Massachusetts not yet dropped out, nor has Rep. Tulsi Gabbard of Hawaii.

But even if Warren and Gabbard stay in the race, they are far behind in delegates and polling suggests they would struggle to reach the 15% viability threshold in upcoming voting contests to earn more.

In a hypothetical situation in which it's Biden versus Bernie on March 17, if the former Vice President dominates in even just three of these states he could come away with a massive lead in the delegates necessary to win the nomination. Polling suggests Biden has a good shot of doing so.

The Vermont senator is ahead in Arizona, with 29.9% of voters in the state backing him, compared to 17.5% for Biden, according to FiveThirtyEight's average for each Democratic candidate in 2020 primary polls. A win there would be a boost to Sanders, but there are also only 67 delegates up for grabs. With Biden likely to earn above 15% of the vote, and the proportional allocation, he is poised to come away with delegates as well.

Meanwhile, Biden is way ahead of Sanders in Florida, with about 28% of voters there saying they back him, compared to 17% for Sanders, according to FiveThirtyEight. This polling average accounts for Bloomberg still being in the race (placing him in second with 24%), but it's still not a good sign for Sanders given the former New York City mayor is a moderate who endorsed Biden.

FiveThirtyEight did not have enough polling to provide an average for Illinois, but Sanders was at the top of the field at 22% with likely Democratic voters in the state in a late February survey conducted by the Paul Simon Public Policy Institute at Southern Illinois University at Carbondale. Biden was in third with 14%, behind Bloomberg with 17%. But with Bloomberg out and now backing the former vice president, Biden could conceivably swallow-up a lot of those voters and potentially defeat Sanders.

Sanders' best numbers for March 17 are in Ohio, where FiveThirtyEight shows him with a double-digit lead over Biden (31% to 21%).

Still, the evidence suggests that the March 17 primaries could be a mixed bag for Sanders. He needs to dominate that day given Biden already has momentum and that could impact results in upcoming contests on March 10, such as the Michigan Democratic primary (the state has 125 pledged delegates).

The Vermont senator is leading in polls in Michigan by a significant margin, but that could shift in the coming days given the boost Biden got via Super Tuesday. Exit polls for Super Tuesday showed that a lot voters made the decision to back Biden in the past few days after his big win in the South Carolina Democratic primary. A similar trend could emerge in the remaining voting contests in March, and by the end of the month roughly two-thirds of all delegates will have been allocated.

Sanders has so far garnered significant support from young and Latino voters, and these voting blocs will continue to be crucial for him moving forward. But if Super Tuesday is any indication of what's to come, Sanders has reason to be nervous. Though young voters overwhelmingly supported Sanders across the board on Tuesday, they also turned out in low numbers and this undoubtedly contributed to his disappointing outcomes in many states.

If young voters fail to turn out in the above states, it could spell the end of his campaign.