It's the worst-kept secret in Maryland that Gov. Martin O'Malley wants to run for president in 2016, but donors have been shy about opening their checkbooks.

O'Malley's O'Say Can You See political action committee took in $47,390 in December after the busy campaign season, and it has $28,550 in the bank, according to a year-end report filed with the Federal Election Commission.

Such PACs are frequently used by candidates to run for office or to support causes. By contrast, supporters of Hillary Clinton -- who has not committed to a 2016 run -- raised $233,871 in December and formed a new PAC last week.

Donors are likely going to be cool about handing candidates cash until the two biggest unknowns of the 2016 Democratic field make a move, and those are Clinton and Vice President Biden, said Todd Eberly, coordinator of public policy studies at St. Mary's College of Maryland.

"I think that at this stage in the game ... it doesn't matter if you're Martin O'Malley, [New York Gov.] Andrew Cuomo or any other possible contenders, because anybody other than Clinton and Biden are second tier, just by the nature of who they are," Eberly said. That hasn't stopped some -- including state workers, CEOs and lobbyists -- from writing checks to O'Malley's PAC.

Maryland State Department of Education member James H. DeGraffenreidt Jr. contributed $1,000, as did former Democratic Connecticut congressman Bruce Morrison, while Ralph S. Tyler III -- city solicitor under O'Malley when he was Baltimore's mayor -- and tech company president Ghanshyam R. Patel donated $5,000 apiece.

O'Say Can You See's biggest expenditures included payments to Blue State Digital for website services and salaries for the PAC's employees and consultants.

The PAC was created in July 2012, to help support what would prove to be successful ballot measures to uphold same-sex marriage and in-state tuition for qualified illegal immigrants. An O'Malley spokesman at the time said the PAC also would support President Obama's re-election campaign. It raised $191,000 throughout 2012, including the December contributions.

O'Malley is term-limited in 2014, though he hasn't explicitly confirmed aspirations for a 2016 presidential run. He came to national prominence as head of the Democratic Governors Association from 2011-2013. In that capacity, he has visited Iowa, New Hampshire, South Carolina and other states that hold early primaries. O'Malley also acted as an Obama surrogate during the election cycle, frequently appearing on Sunday morning talk shows in support of the president.