SPANISH FORT, Ala. — Despite the threat of a possible tropical disturbance moving into the eastern Gulf of Mexico, efforts to contain the oil spill while addressing lingering concerns of the coastal communities affected turned a crucial corner Monday.

BP PLC, the oil giant deemed the “responsible party” for the Deepwater Horizon rig explosion April 20 off the coast of Louisiana, has not announced plans to stop drilling a relief well considered the final step in killing the spill that has ravaged the Gulf Coast for more than 100 days.

While the National Hurricane Center keeps a close eye on the trough of low pressure that could develop tropical characteristics by this evening and barrel toward the central Gulf Coast by Thursday night, BP officials said Monday teams are drilling the final 100 feet of the relief well and could intersect the leaking structure as early as Friday.

National Incident Commander Adm. Thad Allen reiterated Monday the administration’s commitment to continue drilling until the relief well is completed.

“We believe that we have filled the casing with cement and have secured that part of the well. The job before us now is to finish the relief well, to enter the annulus from the bottom, assess its condition, and then seal the well with cement from the bottom up. That will, in our view, at that point, permanently kill the well,” Allen said.

Stopping the oil’s flow permanently is only one side of the equation, however, and Allen took to the talk-show circuit Sunday to drive home that point.

“BP is responsible. We’re going to hold them accountable. And I would say this has been the largest environmental response in the history of this nation, and we’ll continue until the cleanup is done,” Allen told CBS’s “Face the Nation."