Honolulu Mayor Mufi Hannemann raised $583,000 in June alone for a potential campaign for governor in 2010, a take that surpassed his main rival and demonstrates his fundraising prowess.

Hannemann also transferred $659,000 left over from his mayoral campaign to his governor's campaign, giving the mayor $1.2 million in total fundraising.

U.S. Rep. Neil Abercrombie, who announced his campaign in March, raised $486,000.

The congressman has asked the state Campaign Spending Commission to allow him to transfer nearly $1 million from his federal campaign account to his governor's campaign, which would put him on more even footing with Hannemann in a potential Democratic primary.

The commission is expected to make a decision in August.

Hannemann announced in June that he was exploring a possible run for governor.

The mayor held one major fundraiser in June, hosted by attorney Bert T. Kobayashi Jr., and appealed for donations before the June 30 deadline for campaign-finance reporting for the first half of the year.

Candidates often press for donations in advance of campaign-finance reporting deadlines because the figures are used by political analysts and the news media to help determine campaign momentum and strength.

Lt. Gov. James "Duke" Aiona, a Republican candidate for governor, raised $308,000 during the first six months of the year and has collected $1.9 million overall.