Up from the briny deep of the Gulf of Mexico came a nightmare for President Barack Obama. Unlike Hurricane Katrina and its immediate, frightful images of people in crisis, the gushing BP oil well has been a slow-moving behemoth that is now taking a political toll on the U.S. president. Obama was already immersed in a long list of problems — pushing a financial regulation overhaul, prodding Europe to stem a financial crisis, pressuring Iran and North Korea. And don’t forget the 9.9 percent U.S. jobless rate, two wars and Obama’s hopes for immigration and energy legislation before Washington stops for November 2 congressional elections. Now the greatest environmental calamity since the Exxon Valdez spill in 1989 has fallen into his lap. He declared it “heartbreaking.” “We will not rest until this well is shut, the environment is repaired and the cleanup is complete,” Obama said on Wednesday. He makes his second visit to the Gulf on Friday.