Herman Cain’s long-term strategy of building grassroots “infrastructures” through the Tea Party movement gives the Republican front-runner a decisive advantage, his campaign’s controversial chief of staff said Thursday.

“We run a million miles an hour. And you know what? We make mistakes. But they can’t catch us,” Mark Block told me in a telephone interview.

Describing the strategy that led to the campaign’s key breakthrough — an upset victory in the Sept. 24 Florida straw poll — Block talked about “how many dozens of trips that Mr. Cain made into Florida prior to the Florida straw poll and all the Tea Party groups that he spoke at their rallies. … We had built an infrastructure down there. … I remember going into, for God’s sake, Fargo, North Dakota, in February or March, freezing my butt off, and the first people we met was the Tea Party groups, the 9/12-ers, the grassroots organizations. This is why I say that we’re running a million miles an hour — they can’t catch us, Stacy, ‘cause you can’t build those infrastructures overnight.”

Cain has insisted on running his presidential campaign debt-free, and has often been criticized for not having significant paid staff in Iowa, New Hampshire and other early states in the 2012 primary calendar. But that has proved to be an advantage, Block said, now that the campaign’s fundraising has taken off. The campaign said Thursday it has raised more than $9 million since Oct. 1, a pace of $225,000 a day.

“We got a lot of criticism … because we didn’t have a massive staff in every state and we didn’t have a massive staff in Atlanta,” Block said. “And we didn’t have this and we didn’t have that and we didn’t have all this other stuff. . . . Because we didn’t want to burn that cash. So we come out of the Florida straw poll with extremely low fixed costs. If I’m talking like a businessman, it’s because [Cain] runs it like a business. So our burn rate is small, compared to all of the other campaigns, because we don’t have a lot of fixed overhead. So now, as the cash comes in, right, I don’t have a lot of bills to pay.”

The Cain campaign yesterday announced the names of county chairmen in all 67 Florida counties, a list heavy on Tea Party activists, but also including key Republican officials.