Democratic presidential candidate Sen. Bernie Sanders, I-Vt., needs the support of Rep. Alexandria Ocasio-Cortez, D-N.Y., but it could come at a cost, according to "The Five."

Fellow 2020 hopeful Sen. Elizabeth Warren, D-Mass. -- considered Sanders' predominant progressive rival -- should also support any move by Ocasio-Cortez to formally endorse Sanders, Dana Perino and Dagen McDowell claimed Wednesday.

"You know why he wants Alexandria Ocasio-Cortez to help him?" Perino asked.

"He absolutely needs her," she then said, pointing to a resolution co-sponsored by the two progressive lawmakers, as well as Rep. Earl Blumenauer, D-Ore., formally declaring a climate change emergency.

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"His campaign is almost invisible. Think about the debates. Nobody talked about him in the debates. Nobody's talked about him since. He had a pretty good fundraising number, but nobody even talked about that.

"He's got to figure out a way to have some relevance."

Perino continued to say that Warren, as a fellow progressive, could benefit from Ocasio-Cortez sticking with Sanders in the long run.

Expanding upon Perino's comments, McDowell claimed Ocasio-Cortez's controversial comments could be a boon to Warren if the Bronx lawmaker decides to support Sanders.

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"If you get AOC's endorsement, you own that craziness or whatever that she might say that day that's idiotic or irrational," she said.

In Congress, the climate change resolution calls for a wide-scale mobilization to combat the emergency and restore the climate “for future generations.”

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“The global warming caused by human activities,” claims the draft resolution, according to the Mother Jones magazine, “has resulted in a climate emergency that … demands a national, social, industrial, and economic mobilization of the resources and labor of the United States at a massive scale.”

Ocasio-Cortez and Blumenauer, meanwhile, also wrote to fellow members of Congress urging them to declare climate change an emergency in a bid to “swiftly mobilize federal resources in response.”

Fox News' Lukas Mikelionis contributed to this report.