LET'S BE plain about the president's plane, which is yet again the subject of a political spat. Should we care?

Instinctively, you want to say, no, it's silly. But hold on. It is, after all, our plane.

If you missed it, Republicans are barking at the White House over presidential travel.

It's a familiar sound, part of age-old howls about incumbents using the perks of office to further their time in office.

In our state, such howls shouted down several legislative leaders in both parties who've been jailed or will be for misusing public resources for politics.

One who spoke with me not for attribution before going to prison said that his blood boils every time he thinks of presidential trips in election years.

"I go to jail for using tax money for campaigns while president after president gets re-elected using much more tax money to campaign," he said.

So here we go again.

In the case of the moment, GOPers are angry over President Obama jetting around the country promoting his agenda and himself in a re-election year.

Federal election law says that campaign trips must be paid for with campaign funds, but deciding what is a campaign trip, in whole or in part, can be murky business.

Plus, required reimbursements are a fraction of the $179,750-an-hour it costs to operate Air Force One. And unknown tax dollars for security costs, including advance teams, do not require payback.

So, Republicans are irked by Obama's recent campus visits in key electoral states (North Carolina, Colorado and Iowa) to push for more federal aid to help with student loans.

GOP House Speaker John Boehner said that the Obama campaign should repay the Treasury for use of Air Force One on such trips.

"The president traveled across the country on the taxpayers' dime," Boehner said, "insisting that Congress fix a problem that we were already working on."

The White House, using language direct from federal guidelines, called the trips part of Obama's "responsibilities" as president.

Meanwhile, the Republican National Committee filed a formal complaint asking the Government Accountability Office (talk about an oxymoron) to investigate.

To punch its point, the RNC referenced recent egregious abuse by the General Services Administration — the stuff that didn't stay in Vegas, $800,000-plus worth.

Expect others to pile on. Maybe even on Obama's Tuesday trip to Afghanistan.

The hitch in all this is two-fold: it's a rotating partisan issue; it's rife with gray area.

Meredith McGehee is policy director of the Campaign Legal Center, a D.C.-based nonpartisan group tracking campaign finance, elections and ethics.

"This is a quadrennial argument between the political parties," she said. "[T]he big problem is, there's very little public information."

She notes that travel data could be online within 24 hours of each trip saying which parts were political and which were not: "We have none of that. It's kind of a 'trust us' system managed by the White House counsel's office. There are few standards, and while there's legitimate concern about publicizing security costs, that's kind of used as an excuse."

Kathryn Dunn Tenpas, an adjunct poli-sci prof at Penn, runs the university's Washington Semester Program. She's researched and written extensively on incumbent presidential campaigns, and says that every president since Eisenhower has shown a surge in domestic travel in the fourth year of the first term.

She agrees that there's "not a lot of transparency," but also says that the office is inherently political and complaints are inevitable.

"It's Groundhog Day," she says, "and the only way to stop it is to pray for a constitutional amendment creating one six-year term."

So, on one hand, those in power protect and preserve perks while taxpayers pay. And that's unfair. On the other hand, it's ever thus.

And that's the plain truth. n

For recent columns, go to philly.com/JohnBaer. Read his blog at philly.com/BaerGrowls.