Rep. Mazie Hirono raised $624,363 in the three-month campaign finance period that ended on Dec. 31.

According to a summary of campaign finance reports sent to the Federal Election Commission and provided by the Hirono campaign, the U.S. Senate hopeful spent $297,313 last quarter. She has more than $1 million in cash on-hand.

“By more than doubling what we raised during the previous fundraising quarter … it’s clear our momentum is surging heading into 2012,” said Hirono’s campaign finance chair, Jadine Nielsen.

The big question mark from the last quarter is how much did Republican former Gov. Linda Lingle raise? Lingle announced her Senate candidacy in October, so her first campaign finance report will reveal the Lingle campaign’s momentum. That report is due at the end of January.

“Nobody thinks this campaign is going to be easy — especially considering our potential Republican opponent’s vast national fundraising network,” said Hirono’s campaign manager, Betsy Lin in a statement. 

Lin said that the strong year-end showing gives the campaign “all the more confidence” that Hirono can win.