Bernie Sanders, in response to Hillary Clinton's significant delegate lead, has called for wholesale changes to the Democratic Party's primary system, suggesting that is it both un-democratic and tilted in favor of the former secretary of state.
The use of superdelegates, essentially free-agent delegates comprised mostly of Democratic Party stalwarts, many of whom are already backing Clinton, is the primary complaint.
But based on CNN's analysis, major changes to the ways Democrats allocate their delegates, or even abolishing superdelegates, would still result in Clinton holding a large lead over Sanders and close to winning the nomination.
Here's Sanders' path to the nomination, and the results of some alternate scenarios for deciding the Democratic nominee:
Playing for pledged delegates
At this point, Sanders cannot clinch the nomination based on the amount of pledged delegates remaining alone -- he would need to win 110% of the remaining pledged delegates available to reach the magic number of 2,383, according to CNN estimates.
But he still has a mathematical chance of winning more pledged delegates than Clinton, which would help him persuade enough of the 700-plus superdelegates to put him over the top. Since their inception in the 1980s, superdelegates have by and large supported the candidate with the most pledged delegates going into the convention."
"It is a steep hill to climb, and I acknowledge that, but we have the possibility of walking into the Democratic convention with a majority of pledged delegates," Sanders said last week in California.
To accomplish that, Sanders will need to win about 70% of all remaining pledged delegates in the final nine contests, according to CNN estimates.
That would be a significant jump from his performance in the previous 48 contests, where he has won only about 45% of the pledged delegates.
Sanders could pull this off by crushing Clinton in the remaining contests by a 2-to-1 margin. But he's only been able to accomplish that in eight races, and he hasn't hit that level of support since March.
Looking at the calendar, Sanders could run up his numbers in Kentucky, Oregon, Montana, North Dakota and South Dakota. But those states, combined, offer fewer delegates than two upcoming contests where Clinton is expected to perform well: Puerto Rico and New Jersey. So for Sanders to finish with a majority of pledged delegates, he would likely need a blowout of epic proportions in California.
Award all superdelegates to the winner of their state
The key complaint from critics of the nomination process is about the 700-plus superdelegates, free agents who can vote for anyone of their choosing.
They are primarily Democratic members of Congress, governors, mayors and union officials and loyalists.
Clinton has endorsements from 521 superdelegates, and Sanders only has 41, according to CNN's count as of May 18. Given the choice between a longtime party leader, and a political insurgent who only became a Democrat last year, the party elite has clearly rallied behind Clinton.
This commanding lead among superdelegates has pushed Clinton toward officially clinching the nomination. But it has also led to complaints from Sanders that the system is unfair.
"I would hope very much that the superdelegates from those states where we have won with big margins or, in fact, where Secretary Clinton has won with big margins, to respect the wishes of the people of those states and vote in line with how the people of that state voted," Sanders said last week at a speech in Washington.
If the superdelegates from each state were to be awarded as a bloc to the candidate who wins each primary, Sanders would benefit, but still face an uphill climb."
Clinton would have 384 superdelegates, to Sanders' 177. Following these rules, Sanders would have to win about 74% of the remaining pledged delegates to clinch the nomination.
Right now, Sanders has 13 superdelegates in states Clinton won, according to CNN's delegate estimate. Sanders aides have told CNN they will not ask superdelegates from those states to back Clinton. This includes states like Florida, Mississippi and North Carolina, all states Clinton won by double digits.
Award superdelegates proportionally based on state results
What if superdelegates were treated like pledged delegates, divided up proportionally, based on the popular vote in each state?
The Maine Democratic Party recently voted to implement this proposal starting in 2020. Sanders praised the decision and said he hopes "other states follow Maine's example."
It's a scenario that benefits Sanders even more than awarding them all to the winner. That's because he would earn a chunk of delegates from states like New York and Illinois, where he got close, but did not beat Clinton.
Clinton would have 296 superdelegates, and Sanders would have 265. Even with these rules, Sanders would still need about 69% of remaining pledged delegates to clinch the nomination.
Get rid of superdelegates altogether
Superdelegates have become a political problem for the second contested Democratic contest in a row. In 2008, Barack Obama took the overall lead in pledged delegates and used that to convince more and more superdelegates to back him, and Hillary Clinton eventually ended her run.
In both 2016 and 2008, the question is about fairness. Why should a group of several hundred party regulars be in a position to potentially limit or overturn the will of the voters?
Democratic National Committee Chairwoman Debbie Wasserman Schultz said the superdelegates are meant to essentially reinforce the position of the winner in pledged delegates.
"Unpledged delegates exist really to make sure that party leaders and elected officials don't have to be in a position where they are running against grass-roots activists," she told CNN's Jake Tapper in February. "We are, as a Democratic Party, really highlight and emphasize inclusiveness and diversity at our convention, and so we want to give every opportunity to grass-roots activists and diverse committed Democrats to be able to participate, attend and be a delegate at the convention."
So what would happen if superdelegates were eliminated from the 2016 race? According to the math, the results would be about the same of awarding them proportionally.
Eliminating the superdelegates would lower the threshold needed to clinch the nomination to 2,026 delegates. Clinton would still be leading Sanders by nearly 300 delegates.
Under this scenario, Clinton would still only need to win about 33% of the remaining delegates to become the Democratic nominee.