Obama Trips Combine Official, Political Business President Obama jets to Florida today for a mix of official and political business that will steal some headlines in the Sunshine State and line his campaign coffers with at least $4 million. The act of presidential piggybacking -- coupling official duties, in this case a speech on the economy, with political fundraising -- was not pioneered by Obama but is prominently on display this year. Obama has taken four trips outside Washington, D.C., since Jan. 1, including 18 re-election fundraisers interspersed with various activities related to his duties as president. Most recently, Obama concluded a three-day, three-state swing when he attended eight fundraisers and two official events. The president's jet-setting has drawn the usual criticisms from his political opponents but also raised the curiosity and questions from taxpayers about who bears the sky-high costs. Official presidential travel has traditionally been paid for by taxpayers as part of executive branch operations, while political trips and events are to be covered by a candidate's campaign committee. On the occasions that they mix, the costs are to be split. "Most presidents have doubled up on trips and said they followed the law, which is a complex formula no one really understands," said Brendan Doherty, a political science professor at the U.S. Naval Academy and author of the forthcoming book "The Rise of the President's Permanent Campaign." "And even on a fully political trip, the taxpayer ends up paying part of the bill," he said, citing the nature of the American presidency. As a rule of thumb, an incumbent president's campaign is expected to reimburse the government the cost of a first class commercial airline ticket for each person riding Air Force One to or from a political event, campaign finance experts say. But that amount doesn't come close to covering the proportional operating cost of Air Force One, or the army of Secret Service agents, White House advance teams, the fleet of Air Force cargo planes transporting the presidential motorcade or the helicopters that often ferry the president from an airport to a remote site. Air Force One â known in the military as VC-25 â costs $179,750 per flight hour alone in fiscal year 2012, Maj. Michelle Lai of the 89th Airlift Wing told ABC News. That figure includes fuel, flight consumables, depot level repairs, aircraft overhaul and engine overhaul. Pilot and airmen salaries are not included because they are paid regardless of the plane's use, Lai said. Obama's trip to Florida and back today will cost at least $674,000 in Air Force One flight time alone. His three-day, three-state swing that included two official events and eight fundraisers, netting more than $8 million last week, incurred flight costs of $2.1 million, based on the Air Force figure and flight times gathered from press pool reports. As for how the proportion of that bill is broken down for Obama campaign to pay, experts say the law is murky and the practice of reimbursement somewhat "on your honor." "At the end of the day the Federal Election Commission has not been abundantly clear about how the costs of mixed purpose travel should be paid for," said Paul Ryan, an expert in FEC law with the Campaign Finance Institute. Ryan said a recent advisory case involving Sen. Scott Brown, R-Mass., who wanted to attend fundraisers while traveling on a publisher-paid book tour, illustrates the lack of clarity in this area of election law. The FEC deadlocked on the question of whether Brown's campaign committee had to foot any of the travel costs, with the panel's Republican members insisting that Brown shouldn't have to pay any at all. "The rationale was that he was going to the cities principally for the book tour, and he would be there regardless of whether or not he was holding a fundraising event," Ryan said. They believed that fact he tacked on a fundraising event didn't trigger a recharacterization of the travel. "I think the same analysis would apply to Barack Obama's travel," he said. The Obama campaign has reimbursed more than $1.5 million for travel so far this election cycle, according to FEC records. White House press secretary Jay Carney explained last week that the administration follows all guidelines and precedent for mixed purpose presidential travel, often "consolidating" events on long-range trips to maximize the value. "We do it absolutely by the book -- in the same manner that President Bush did, President Clinton did," Carney told reporters on Feb. 16. Richard Painter, an associate counsel in the George W. Bush administration and chief ethics lawyer for the president between 2005 and 2007, said he believes Obama's travels -- like Bush's -- are legal and necessary, despite the high cost. "The argument for taking Air Force One and everything else, even for campaign events, is that the president needs to travel in a secure way and have communications capabilities," Painter explained. Obama in Miami, Orlando After a speech on his 2013 budget proposal at the University of Miami, Obama will attend three fundraisers for his re-election campaign. He'll attend a reception with 450 supporters at the Biltmore Hotel in Coral Gables, where DNC chairwoman Debbie Wasserman Schultz and Sen. Bill Nelson would also join, and singer Deborah Cox will perform. General admission tickets were $1,000 apiece, a campaign official said. Then Obama will hobnob at a private residence in Coral Gables with 100 donors, who each paid at least $15,000 for a chance to meet the president. Obama will fly Air Force One from Miami to Orlando for his third event of the evening, at the Windermere home of NBA star Vince Carter. Each of the 70 guests cut a check of $30,000, according to the Obama campaign. All proceeds benefit the Obama Victory Fund, a joint account of the Democratic National Committee and president's campaign. Obama Logs 10K Miles Obama's Florida fundraisers raise his total for the year to 28, including events in Democratic-strongholds of Illinois, New York and California. Combined, Obama has logged more than 10,000 flight miles this year on trips that have included fundraisers.