WASHINGTON -- To save time and drilling costs, BP took "shortcuts" that may have led to the Gulf of Mexico oil rig explosion and the spill, according to a letter released Monday by two House Democrats leading an investigation of the disaster.

The letter, in advance of congressional hearings with senior oil executives this week, paints a damning picture of five decisions the lawmakers said the oil firm took "to speed finishing the well," which was running "significantly behind schedule."

Marshaling e-mails, interviews and documents, the lawmakers said: "In effect, it appears that BP repeatedly chose risky procedures in order to reduce costs and save time, and made minimal efforts to contain the added risk."

In one instance, just four days before the April 20 explosion, Brett Cocales, one of BP's operations drilling engineers, sent an e-mail to a colleague noting that engineers had not taken all the usual steps to center the steel pipe in the drill hole, a standard procedure designed to ensure that the pipe would be properly cemented in place. "[W]ho cares, it's done, end of story, will probably be fine and we'll get a good cement job," he wrote.

BP did not respond Monday, and Mr. Cocales could not be reached to comment. "It would be inappropriate for us to comment ahead of the hearing," said BP spokesman Andrew Gowers.

The letter was part of another very bad day for BP. The company's stock dropped 9 percent, to $30.67 a share. Investors fretted about a White House meeting Wednesday between top BP directors and President Barack Obama, who will also make the oil spill the centerpiece of his first Oval Office address at 8 p.m. tonight.

Speaking Monday inside a large shelter at a Coast Guard clean-up staging area in Theodore, Ala., Mr. Obama vowed that "we're going to continue to hold BP and any other responsible parties accountable for the disaster that they created."

White House officials said they were working to strike a deal with the oil giant on a multibillion-dollar escrow account to compensate victims.

Mr. Obama made a swing Monday though Mississippi, Alabama and Florida. "There are still problems" with the claims process, he said after a briefing in Gulfport, Miss., with several governors, Coast Guard officials and other response officials.

Flanked by Mississippi Republican Gov. Haley Barbour and Coast Guard Admiral Thad Allen, the incident commander, the president said the discussion included how best to coordinate skimmers and other boats already on the gulf to prevent the slick from coming ashore, as well focusing on the claims issue.

House Energy and Commerce Committee Chairman Henry A. Waxman, D-Calif., and Rep. Bart Stupak, D-Mich., chairman of its oversight and investigations subcommittee, sent a 14-page letter to BP Chief Eexecutive Tony Hayward, who will testify Thursday before the committee.

After reviewing documents and interviews the panel obtained, the lawmakers said, "BP appears to have made multiple decisions for economic reasons that increased the danger of a catastrophic well failure."

The money that BP allegedly saved seems trivial now, in light of the blowout that killed 11 Deepwater Horizon rig workers and led to the oil spill that has polluted large swaths of the gulf. But given the daily costs of $1 million to $2 million to run a drilling rig, they appear to have been a big factor in decision-making.

The two lawmakers wrotethat their investigation is "raising serious questions" about decisions made in the days and hours before the explosion on the drilling rig that later sank.

According to the committee's investigation, other BP decisions that "posed a tradeoff between cost and safety" included:

• BP saved $7 million to $10 million by using a more risky option for the well casing, or steel tubing.

• BP decided against a nine- to 12-hour procedure known as a "cement bond log" that would have tested the integrity of the cement.

• BP did not fully circulate drilling mud, which would have taken as long as 12 hours. That would have helped detect any pockets of gas, which later shot up the well and exploded on the deck of the drilling rig.

• BP did not secure the connections, or casing hangers, between pipes of different diameters.

Washington correspondent Daniel Malloy writes the "Pittsburgh On The Potomac" blog exclusively at PG+, a members-only web site of the Pittsburgh Post-Gazette. Our introduction to PG+ gives you all the details.