Honolulu Mayor Peter Carlisle, seeking to retain the job for a full four-year term, reported raising $53,000 in the last half of 2011, according to a report filed Monday with the state Campaign Spending Commission.

Former city Managing Director Kirk Caldwell reported raising $72,000 in the reporting period, according to his campaign spending report filed today.

Former Gov. Ben Cayetano entered the race earlier this month and did not have any donations to report in the current filing period.

All three are expected to compete heavily in the mayor’s race. Cayetano has said he expects to need about $500,000 for the race to unseat Carlisle. Caldwell has pegged the number higher, at about $800,000 to $1 million.

Carlisle has raised $340,000 in the current election cycle and had about $297,000 in cash on hand to end 2011. He carried over $89,000 from his 2010 campaign.

Carlisle has done little in the way of campaigning — both challengers declared their bids against him within a week of each other earlier this month. His campaign has said he is focused on the day-to-day operations of running the city and continues to seek ways to trim government spending as he prepares his operating budget for the upcoming fiscal year.

He opened his campaign headquarters last week.

Despite declaring for the race just this month, Caldwell had previously held fundraisers with an eye on the mayor’s race. Caldwell campaign chairman Lex Smith said he remains encouraged by early fundraising efforts noting that virtually all of the latest donations were reported in the last six weeks of 2011. Caldwell still carries a personal campaign debt of about $188,000 from the 2010 race.

Carlisle won a special election in 2010 to fill the final two years of the term vacated by Mufi Hannemann, who resigned to run for governor. He won with a plurality among four major contenders, capturing 38.8 percent of the vote. Caldwell finished second, with 34.6 percent, despite outspending Carlisle by a margin of about 2-to-1.

In a regular election year, one candidate can win with 50 percent plus one vote in the Aug. 11 primary. Otherwise, the top two finishers advance to a run off in the November general election.