Former Florida state House Speaker Marco Rubio (R) announced Thursday that he has raked in more than $860,000 for his Senate campaign since the beginning of the month via his online fundraising efforts.

That total, raised from more than 11,000 donors, is equal to about half the $1.75 million that Rubio raised during the last three months of 2009. Rubio reported just more than $2 million in the bank at the end of last year.

But Rubio will likely need all the cash that he can get considering his primary opponent, Gov. Charlie Crist, has consistently been one of the top Senate fundraisers this cycle. Crist raised $2 million from October to December and reported more than $7.5 million in cash on hand as of Dec. 31.

Rubio’s “stimulusbomb” fundraising campaign (a take on the “money bomb” online fundraisers that are becoming increasingly popular) was timed to coincide with the one-year anniversary of Crist’s public declaration of support for President Barack Obama’s 2009 stimulus plan. Crist has since said that he would not have supported the final version of the bill.

Despite the fact that Crist began the primary as the unquestioned frontrunner — and as the preferred candidate of the National Republican Senatorial Committee — Rubio has found traction running to the right of the governor, and recent polling has shown the primary is competitive. Rubio has earned the endorsement of key conservatives in Congress, including Sen. Jim DeMint (R-S.C.) and Rep. Mike Pence (R-Ind.), as well as conservative interest groups like the anti-tax Club for Growth.

DeMint’s Senate Conservatives Fund political action committee was a major supporter of Rubio’s stimulusbomb event, helping to raise about $140,000 for the effort.

“I’m encouraged by the support we’ve received this month from people who believe a return to limited government is what will keep America free and prosperous,” Rubio said in a statement. “We are pleased with our progress, but also realize we have a long way to go to compete with one of the most prolific fundraisers in political history.”