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(CNN) —  

Julián Castro announced Monday in an email to supporters that his presidential campaign needs to raise $800,000 by the end of October or he will end his 2020 bid.

The fundraising tactic is a last-ditch effort for a candidate who has struggled to raise money for much of his campaign; he entered the fourth quarter of 2019 with less than $700,000 in the bank. In the email, the former Housing and Urban Development secretary writes that the donations are needed to help him qualify for November’s Democratic debate, something he has failed to do so far.

“I’m asking you to fight for me like never before,” Castro says in the email. “If I don’t meet this deadline, I won’t have the resources to keep my campaign running. I’m counting on your $5 in this critical moment.”

He adds: “This isn’t a fundraising gimmick — it’s the transparency and honesty I have promised you since I entered this race. The truth is, for our campaign, these debates have offered our only guaranteed opportunity to share my vision with the American people. If I can’t make the next debate stage, we cannot sustain a campaign that can make it to Iowa in February.”

Castro actually has met the fundraising threshold to qualify for the fifth debate. However, he has failed to reach the polling threshold.

“The campaign needs a significant influx of resources to fund operations needed to secure his spot on the November debate stage,” an aide said Monday. “To secure these polls, the campaign will need an influx of resources to fund operations in battleground states.”

Castro is not the first campaign to tie dropping out of the race to a fundraising strategy. New Jersey Sen. Cory Booker, ahead of the third quarter deadline in September, said he would drop out of the race unless he raised $1.7 million in the final days of the quarter. Booker topped that fundraising threshold and has continued his campaign.

“Our campaign is facing its biggest challenge yet,” campaign manager Maya Rupert said in a statement. “Secretary Castro has run a historic campaign that has changed the nature of the 2020 election and pushed the Democratic party on a number of big ideas. Unfortunately, we do not see a path to victory that doesn’t include making the November debate stage—and without a significant uptick in our fundraising, we cannot make that debate.”

Former Texas Rep. Beto O’Rourke also tried a similar tactic this earlier this month. His campaign manager, Jen O’Malley Dillon, said they need to raise $2 million in the first six weeks of the fourth quarter. However, Dillon did not say O’Rourke would end his campaign if they fail to reach their goal.