The Bernie Sanders campaign is ready to make their closing argument to the Democratic Party, pointing to polls that show him as the only candidate able to defeat Donald Trump in November.

Facing a deficit of nearly 300 pledged delegates to Hillary Clinton and some unfavorable contests on the horizon, Bernie Sanders has little hope of passing Clinton in the race for the Democratic nomination. But Clinton is also unable to reach the mark by wins alone, and will need some of the party’s 700 superdelegates to put her over the top. That could leave an opening for Sanders to still win, despite what seems to be long odds.

While many of the superdelegates already aligned with Clinton, Bernie Sanders is making an all-out push to win them over and is pointing to polls showing his strength. In a press release issued this weekend, Sanders noted that his head-to-head lead over Donald Trump in polls is three times that of Clinton’s.

“Democrats seeking a presidential nominee to lead their party to victory in November should take notice of the overwhelming preponderance of data demonstrating that Bernie Sanders is the strongest Democratic candidate to defeat Donald Trump,” according to analysis by Sanders’ pollster, Ben Tulchin.

The Sanders camp noted his advantage among young voters and independents, two blocs that will be important in November. The Vermont senator’s popularity is another boost, his camp said.

“This positive profile stands in stark contrast to both Hillary Clinton and Donald Trump, who are both deeply unpopular,” Tulchin wrote in the memo released Saturday. “Clinton’s favorables are 31 percent to 52 percent unfavorable while Trump is slightly more unpopular.”

The push to win over superdelegates comes after what may have been the worst week of the campaign for Hillary Clinton. She remains dogged by questions over her FBI investigation and a continued refusal to release transcripts of speeches made to Wall Street firms, and this week Donald Trump overtook her in a series of national polls.

Bernie Sanders has continued to press Hillary Clinton, even calling on her this week to follow through with a promise made earlier in her campaign to have a debate in May. Sanders has pressed Clinton to agree to a debate in California, the delegate-rich state targeted by the Sanders campaign as a chance to take a massive chunk out of Clinton’s delegate lead and make his case to superdelegates that much easier.

Bernie Sanders Strongest Candidate to Beat Trump https://t.co/wJenaQCjXh — My name is (@RevoltPolitic) May 21, 2016

“Both campaigns have been invited by Fox News to a debate. We have told the network that we would accept the invitation with the understanding that we can reach mutual agreement on the debate moderators, the format and other details,” Sanders campaign manager Jeff Weaver said, via the Washington Times. “More than half way through the month of May, we hope Secretary Clinton will soon make good on her campaign’s commitment and agree to a time and place for a debate. There are issues of enormous importance facing the people of California and our nation and the people of our largest state deserve to hear the Democratic candidates opinions.”

Defiant @BernieSanders vows to stay in race until last ballot is cast. pic.twitter.com/KJJZ0qwwqq — Fox News (@FoxNews) May 21, 2016

Hillary Clinton has also struggled to win over voters currently aligned with Bernie Sanders. The New York Times noted that distrust of Clinton is high among Sanders voters.

“Mrs. Clinton is still contending with resistance to her candidacy from supporters of Mr. Sanders as their contest carries on and grows more contentious. Twenty-eight percent of Mr. Sanders’s primary voters say they will not support her if she is the nominee, a figure that reflects the continuing anger many Sanders supporters feel toward both Mrs. Clinton and a process they believe is unfair.”

The report noted that this same scene has played out before, with 60 percent of Clinton voters saying in 2008 that they would not vote for Barack Obama, a number that faded as the campaign went on and most moved into Obama’s corner. By contrast, 72 percent of Sanders voters say they plan to vote for Clinton if she becomes the nominee.

But Bernie Sanders will likely need more than good head-to-head polls against Donald Trump to make his case for the Democratic nomination. With so many superdelegates already committed to Clinton — some having aligned with her even before voting began this year — he will need to make a run in the remaining primaries and cut her lead as much as possible.

[Photo by Mark Wilson/Getty Images]