Washington ? President Barack Obama has been trying mightily to show that he’s in charge of the Gulf oil spill, not battered BP.

It may be working. It’s another question whether that’s good politics for the president.

Obama made his third visit to the Gulf on Friday, criticizing BP for spending money on advertising to repair its tarnished image and paying dividends to shareholders in the midst of a crisis.

“I want BP to be very clear, they’ve got moral and legal obligations here in the Gulf for the damage that has been done,” Obama said.

“We’ve assigned federal folks to look over BP’s shoulder” to make sure they honor those obligations, the president said.

The more responsibility the president assumes, the more he opens himself up to criticism when things go wrong. And very little about the spill can go right. Even once the leak is plugged, which won’t be until August at the earliest, the oil will remain for months or years to come. For Obama, the danger is that the horrible mess will mire him down as surely as it is the Gulf’s ecosystem.

“It’s got awful political consequences for him in the short run,” said Stephen Hess of the Brookings Institution. “Why? Because the usual rule of thumb in presidential politics is that a president gets credit for anything that goes well on his watch and gets blamed for bad things. And this is a big bad thing.”

Still, Obama had little choice but to assert control, something that Americans demand of their leaders in time of crisis. With the oil giant BP PLC seen as bungling and untrustworthy, Obama had to show he was pushing them aside.

Taking the credit

Ideally, he’ll get credit for taking control while leaving the anger at BP’s doorstep. Obama himself has argued that history will find he took the right steps in response to the spill. But it’s hardly a sure bet.

“You could write one of two stories: Either he’s doing too much, or he’s not doing enough.” Given the choice, White House press secretary Robert Gibbs said in an interview, “you’d want to do more.”

Bad news stories don’t inevitably hurt presidents. Take George W. Bush’s response to the Sept. 11 attacks, Bill Clinton’s response to the Oklahoma City bombings or Ronald Reagan’s reaction to the space shuttle Challenger disaster. Those were all instances in which, at least initially, the nation rallied behind the president in face of disaster.

Obama, with his cool manner and cautious tendencies, arguably has still not made the emotional connection with the public that some of his predecessors did in times of trouble. But unlike those previous disasters, the Gulf spill is a calamity with no end point. In that sense, it’s more comparable to the Iran hostage crisis that crippled Jimmy Carter’s presidency than it is to Hurricane Katrina.

For Carter, there was no question whose responsibility it was to solve the problem. It was his. He didn’t deliver as the crisis dragged on for 444 days and partly as a result, he was denied re-election. Obama must walk a fine line between being engaged in the response to the spill and becoming so sucked into it that the rest of his agenda grinds to a halt and he’s held personally responsible for every false step.

So even as Obama’s administration takes an increasingly muscular stance — ending joint briefings with BP, calling the shots on technical approaches toward stanching the spill, launching a criminal investigation — Obama still takes care to note that BP caused the spill and is accountable for cleaning it up. At the same time, he insists that the ultimate responsibility is his and that BP must do what he tells them to.

It’s a message that can sound a bit muddled, especially when BP appears to be contradicting the federal government on the extent of the pollution, or failing to execute the federal government’s commands. Obama and his administration also have avoided, so far, the harshest condemnations of BP.

Ultimately, Obama will be judged by the outcome, making the deliberations over the wisdom of this or that move along the way moot. So in the short term, perhaps the best Obama can hope for is that the public assigns him an “A” for effort — or at least a passing grade — and heeds his reminders that though he may own the spill now, BP started it.