WASHINGTON (CN) - The White House ramped up the response to the oil spill in the Gulf of Mexico, with President Obama calling for the administration to use "every single available resource" to address the spill. The spill, which could be the worst in U.S. history, may prompt Obama to adjust his plans to expand offshore drilling.
"While BP is ultimately responsible for funding the cost of response and cleanup operations, my administration will continue to use every single available resource at our disposal, including potentially the Department of Defense, to address the incident," Obama said in a Rose Garden speech Thursday afternoon.
White House Press Secretary Robert Gibbs said the administration is being "aggressive in our response," including considering sending out SWAT teams and deploying U.S. naval resources to inspect platforms and rigs and set up booming and skimming systems. More than 1,100 people are engaged in emergency response efforts.
On Thursday, Homeland Security Secretary Janet Napolitano declared the BP disaster "a spill of national significance," enabling the White House team to call in a vast array of resources from across the country to address the crisis.
Napolitano is traveling to the Gulf on Friday with Interior Secretary Ken Salazar and Environmental Protection Agency head Lisa Jackson to assess the damage.
National Oceanic and Atmospheric Administration estimates put the spill at more than 5,000 barrels of oil a day -- more than 200,000 gallons. The number jumped five times from initial estimates of 1,000 barrels per day. The damage threatens to approach the 1989 Exxon Valdez disaster, which spilled more than 250,000 barrels, or 1.26 million gallons, when it ran aground.
BP is using a variety of tactics to combat the spill, including controlled open sea burning, chemical dispersants and surface skimming. It's also trying to close a shut-off valve, the most promising solution for containing the spill. Another option is to construct a cofferdam that is placed just above the leak, which collects the oil and pumps it to the top. In the worst case scenario, responders will drill a relief well next to the original well, which could take up to 90 days.
The spill threatens to touch the shores of five U.S. states: Louisiana, Alabama, Mississippi, Florida and Texas.
The slick hit the Louisiana shore Friday, washing up on wetlands at the mouth of the Mississippi River.
The spill is the result of an April 20 explosion on the Deepwater Horizon drilling platform in the Gulf of Mexico, which left 11 workers missing and presumed dead.
Gibbs said the results of a joint investigation as to what caused the crisis could affect the president's stance on drilling. The Departments of Interior and Homeland Security have already started the investigation.
"We need to figure out what happened," Gibbs said in a press briefing. "Would a finding of something possibly affect that? Of course."
White House Energy Director Carol Browner said the president's plan to expand drilling is just that -- a plan. But she also suggested that it could be adjusted.
Obama is experiencing political backlash from the spill. On Thursday, Democratic Sen. Bill Nelson of Florida sent a letter to Obama calling for "an immediate halt to test wells and all other exploratory operations in coastal waters."
Nelson said he's filing legislation that would block the Interior Department from going ahead with the president's plans to expand offshore drilling, seismic testing and other exploratory operations.
Nelson warned that the spill "may be an environmental and economic disaster that wreaks havoc for commercial fishing and tourism along the Gulf of Mexico coast."
Read the Top 8
Sign up for the Top 8, a roundup of the day's top stories delivered directly to your inbox Monday through Friday.