Cain campaign reports more than $3 million raised in October

(CNN) - Herman Cain's chief-of-staff, Mark Block, said on CNN Thursday night the campaign has raised more than $3 million since the beginning of October and reported 65,000 donors.

"We've actually doubled in a little over a month, and that's what we're seeing in our grassroots activism growth," Block said on CNN's "Out Front with Erin Burnett."

The figure represents a huge surge in the campaign's fundraising, and totals more than money raised in the previous three previous months combined.

From July through September, the campaign reported raising more than $2.8 million, which includes a $175,000 loan from Cain, according to the campaign's finance reports filed with the Federal Election Commission.

The spike corresponds with Cain's big leap in the polls during the last month. While he was hovering in the single digits until late September, he now finds himself at the top competing with former Massachusetts Gov. Mitt Romney in most national surveys.

Block hit back at criticism over Cain not being as active as other candidates in key early voting states, including New Hampshire and Iowa, while he spends time on a book tour across the South.

"I think when this is all said and done, you will see that we have one of the most strongest, widespread and deep grassroots organizations all across America," Block said, adding that the campaign has organizations in all 50 states.

Block made headlines earlier this week for starring - and smoking - in a web video for Cain's campaign. The video has since gone viral, with nearly a million hits as of Thursday night.

- CNN's Robert Yoon contributed to this report.

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