Jeff Weaver, Sanders’ campaign manager, was on an afternoon call with reporters on Wednesday, sunnily explaining the path forward for his candidate, who faces increasingly long odds to win the nomination. His campaign had lost five states on Tuesday and left Sanders with a more-than-300 delegate gap behind to Clinton, who has won twice as many states. But Sanders can win if he stays on, Weaver argued.

Then—without being asked whether the Vermont Senator should drop out—Weaver suggested Sanders is Clinton’s shield against Donald Trump.

“Were this contest to end, you know, by Secretary Clinton, or us getting out—certainly if the Secretary were still in the race, she could expect months and months and months of immediate, and vicious, and very personal attacks from the Trump people,” Weaver said. “So I don’t know if that’s necessarily healthy for her.”

It was a hint, perhaps, at how difficult Sanders’ aides believe his chances of being the Democratic nominee are. It was also one of the many reasons, ranging from the noble to the hopeful and the dubious, that Sanders says he will be staying in the race until the Democratic convention in July.

Whatever Sanders does, Hillary Clinton welcomes a long contest. After all, she battled Barack Obama to the finish line in 2008. “It’s his campaign to run as he chooses,” Clinton said in an interview with ABC before the results rolled in on Tuesday. “I’m not ever going to tell anybody that they should drop out.”

Here are four more reasons why Sanders’ aides say he will soldier on:

The second half of the primary will be good to Sanders

The primaries just ahead in the calendar, Sanders aides argue, are auspicious for the Vermont Senator and look more like the Northern states he has already won than the Southern, heavily African-American states he has lost. Arizona looks like Colorado, Wisconsin is like Minnesota, Washington is a bit like Vermont.

“We have always understood that the first half of the calendar was much more advantageous to the Secretary,” said Weaver. Wins in the second half of the primary schedule, Sanders aides say, will help them close the gap with Clinton. And with the grassroots money-making machine Sanders has, funds will not be difficult to come by.

Clinton’s pledged delegates may not be so pledged

Although the Democratic pledged delegates are bound to a particular candidate based on state Democratic votes, Sanders senior strategist Tad Devine suggested there is some leeway there. Devine pointed to the Carter campaigns 1980 victory and their worry about holding onto pledged delegates. The Carter campaign was “deeply concerned about the defection of pledged delegates” to Ted Kennedy, Devine said.

“My point is that a frontrunner in a process like this needs to continue to win if you want to keep hold of delegates,” Devine continued. When pressed by a reporter, Devine said there was no plan “at the moment” to try to sway pledged delegates.

The less hectic primary schedule helps Sanders

The states in the coming months are spaced out, with more time between primaries. Arizona, Idaho and Utah are on March 22, and Washington, Hawaii and Alaska about a week after that. But fewer delegates are at stake on each days.

Sanders, his aides say, has done best and often defeated Clinton in states he has spent more time in and been able to introduce himself, including states like Michigan, New Hampshire or Iowa. “Almost everywhere we compete with her, even places that we lose, we turn around huge margins,” Devine said. “We can walk into place where we’re 20 points behind and in a couple weeks we can tie her or we can beat her.” It should be noted Sanders has also lost in places he has competed hard, like Ohio and North Carolina.

If Sanders drops out now, millions of Democrats would not vote

Weaver said that Sanders would deprive Democrats of their chance to participate in the primary if he drops out now. “Not even half the delegates have been picked and I think it is not good for a media drumbeat to essentially disenfranchise half the Democratic voters in this Democratic primary and caucus system,” Weaver said. “We believe voters should have a chance to articulate which candidate they would support.”

This article was originally published on Time.com.