President Obama has described as a positive sign BP's statement that oil has, at least temporarily, stopped leaking into the Gulf of Mexico from the Deepwater Horizon well site.  President commented briefly on the issue after returning from a visit to Michigan.

Video of the Deepwater Horizon well site deep below the surface of the Gulf of Mexico showed a new more tighly-fitting cap installed by BP having stopped the flow of oil into the ocean.

After delivering a main statement on the U.S. Senate's passage of a sweeping financial system reform bill, the president responded this way when asked about the development.

"I think it is a positive sign," said President Obama. "We are still in the testing phase, I'll have more to say about it tomorrow."

Caution was understandable considering a statement from BP Thursday about the operation in the Gulf.

BP said while it was expected no oil would be released during a pressure integrity test this could not assured, adding that even stoppage during testing would not indicate that oil and gas flow had permanently stopped.

BP said it had temporarily halted drilling operations on relief wells, which the company says remain the sole means to permanently seal and isolate the Deepwater Horizon well site.

If the latest BP capping operation does succeed in stopping the oil flow, it will be the best of news for people in Gulf states struggling with economic and environmental devastation from the nearly three month ordeal.

It would be good news too for President Obama, who faced sharp criticism that his administration was slow to respond to the initial explosion of the Deepwater Horizon oil rig on April 20, which killed 11 crewmen.

The president has made clear he intends to maintain pressure on BP to fulfill obligations it has made to pay compensation to Gulf coast residents, through a $20 billion fund negotiated with the administration, and finance ongoing containment and cleanup operations.

It remains to be seen whether a successful stoppage of oil flowing into the Gulf will strengthen the president politically in coming months, after he faced tough polling numbers regarding his handling of the disaster.

The president also faces ongoing pressure from Gulf state politicians over a new six month moratorium on deepwater oil drilling announced this week.  Mr. Obama says this was necessary because of ongoing uncertainty about safety in the wake of the Deepwater Horizon disaster.

Steps are continuing in the U.S. Congress to dramatically change existing U.S. laws regarding offshore oil drilling, including imposing new environmental safeguards, with numerous pieces of legislation awaiting action.