NEW ORLEANS -- After insisting for months that a pair of costly relief wells were the only surefire way to kill the oil leak at the bottom of the Gulf of Mexico, BP officials said Monday that they might be able to do it just with lines running from a ship to the blown-out well a mile below.

As crews planned testing to determine whether to proceed with a "static kill" to pump mud and perhaps cement down the throat of the well, BP Senior Vice President Kent Wells said if it's successful the relief wells might not be needed after all.

The primary relief well, near completion, still will be finished and could be used simply to ensure the leak is plugged, Wells said.

"Even if we were to pump the cement from the top, we will still continue on with the relief well and confirm that the well is dead," he said. Either way, "we want to end up with cement in the bottom of the hole."

A federal task force says about 172 million gallons of oil made it into the Gulf between April and mid-July, when a temporary cap bottled up all the oil.

That number is on the high end of recent estimates that anywhere from 92 million to 184 million gallons had gushed into the sea.

The company began drilling the primary, 18,000-foot relief well May 2, 12 days after the Deepwater Horizon rig exploded and killed 11 workers, and a second backup well May 16. The first well is now only about 100 feet from the target, and Wells said it could reach it as early as Aug. 11.

"Precisely what the relief wells will do remains to be seen given what we learn from the static kill," BP spokesman Daren Beaudo said. "Can't predict it for certain."

Retired Adm. Thad Allen, the government's point man on the spill response, said Monday that the focus is on making sure the static kill is successful. But he cautioned that federal officials don't see it as "the end all, be all until we get the relief well done."

One of the biggest variables is whether the area called the annulus, which is between the inner piping and the outer casing, has sprung an oil leak. Engineers probably won't be able to answer that question until they drill in from the bottom, he said.