Outbound traffic creeps along Interstate 66 across the Potomac River from Washington, in Arlington, Virginia, after a major winter storm snarled rush hour traffic in the nation’s capital, Wednesday, Jan. 26, 2011. (AP Photo/J. David Ake)

Outbound traffic creeps along Interstate 66 across the Potomac River from Washington, in Arlington, Virginia, after a major winter storm snarled rush hour traffic in the nation’s capital, Wednesday, Jan. 26, 2011. (AP Photo/J. David Ake)

President Barack Obama delivers his State of the Union address at the Capitol in Washington, Tuesday, Jan. 25, 2011. (AP Photo/Evan Vucci)

President Barack Obama delivers his State of the Union address at the Capitol in Washington, Tuesday, Jan. 25, 2011. (AP Photo/Evan Vucci)

The sun illuminates the clouds with the Washington Monument below as seen from Capitol Hill in Washington, Monday, Nov. 29, 2010. Flash flood watches have been posted for the Washington metro area for the Tuesday and Wednesday as heavy rain is expected. (AP Photo/Alex Brandon)

The sun illuminates the clouds with the Washington Monument below as seen from Capitol Hill in Washington, Monday, Nov. 29, 2010. Flash flood watches have been posted for the Washington metro area for the Tuesday and Wednesday as heavy rain is expected. (AP Photo/Alex Brandon)

A sign helps explain the new technology to travelers at a TSA security checkpoint at Washington’s Ronald Reagan Washington National Airport, Wednesday, Nov. 24, 2010, as the holiday travel season began. (AP Photo/Alex Brandon)

A sign helps explain the new technology to travelers at a TSA security checkpoint at Washington’s Ronald Reagan Washington National Airport, Wednesday, Nov. 24, 2010, as the holiday travel season began. (AP Photo/Alex Brandon)

An unidentified woman stands at a bus stop along South 9th Street in downtown Tacoma, Washington, as snow falls Monday morning, Nov. 22, 2010. People in most of Eastern Washington were told Monday to prepare for a rare blizzard as the first severe storm of the winter blasted through the state, though weather officials said it was too early to tell if the rough weather would affect Thanksgiving holiday travel later in the week. (AP Photo/The News Tribune, Janet Jensen)

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An unidentified woman stands at a bus stop along South 9th Street in downtown Tacoma, Washington, as snow falls Monday morning, Nov. 22, 2010. People in most of Eastern Washington were told Monday to prepare for a rare blizzard as the first severe storm of the winter blasted through the state, though weather officials said it was too early to tell if the rough weather would affect Thanksgiving holiday travel later in the week. (AP Photo/The News Tribune, Janet Jensen)

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Fog envelopes Capitol Hill in Washington, at dawn Monday, Nov. 15, 2010, as Congress begins its lame duck session following a long break for the midterm elections. (AP Photo/J. Scott Applewhite)

Fog envelopes Capitol Hill in Washington, at dawn Monday, Nov. 15, 2010, as Congress begins its lame duck session following a long break for the midterm elections. (AP Photo/J. Scott Applewhite)

The U.S. Capitol and House of Representatives is seen through fall foliage on election day in Washington, Tuesday, Nov. 2, 2010.(AP Photo/Alex Brandon)

The U.S. Capitol and House of Representatives is seen through fall foliage on election day in Washington, Tuesday, Nov. 2, 2010.(AP Photo/Alex Brandon)

An eight-week-old female lion cub swims through fall leaves during a swim test at the National Zoo in Washington, Tuesday, Oct. 26, 2010. The test was to make sure the four cubs will be safe around the water feature when they are put on public display, which is expected to take place in late December. The test was very successful according to the lion keepers. (AP Photo/Jacquelyn Martin)

An eight-week-old female lion cub swims through fall leaves during a swim test at the National Zoo in Washington, Tuesday, Oct. 26, 2010. The test was to make sure the four cubs will be safe around the water feature when they are put on public display, which is expected to take place in late December. The test was very successful according to the lion keepers. (AP Photo/Jacquelyn Martin)

Trees begin to show their autumn colors on the east grounds of the Capitol in Washington, Tuesday, Oct. 26, 2010. (AP Photo/J. Scott Applewhite)

Trees begin to show their autumn colors on the east grounds of the Capitol in Washington, Tuesday, Oct. 26, 2010. (AP Photo/J. Scott Applewhite)

Waves crash on rocks near a house at Alki Point in West Seattle, Monday, Oct. 25, 2010. A strong storm system brought wind and waves to coastal areas and snow to higher elevations in Washington state. (AP Photo/Ted S. Warren)

Waves crash on rocks near a house at Alki Point in West Seattle, Monday, Oct. 25, 2010. A strong storm system brought wind and waves to coastal areas and snow to higher elevations in Washington state. (AP Photo/Ted S. Warren)

The sixth Boeing 787 test plane moves into position for take off on its first flight Monday, Oct. 4, 2010, from Paine Field, in Everett, Washington. (AP Photo/Elaine Thompson)

The sixth Boeing 787 test plane moves into position for take off on its first flight Monday, Oct. 4, 2010, from Paine Field, in Everett, Washington. (AP Photo/Elaine Thompson)

Seen through a fish-eye lens, stunt pilot Sean D. Tucker, flying for Team Oracle, practices aerobatics above Puget Sound near Seattle, Thursday, Aug. 5, 2010. Tucker was preparing for performances at this weekend’s Seafair air show over Lake Washington in Seattle. (AP Photo/Ted S. Warren)

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Seen through a fish-eye lens, stunt pilot Sean D. Tucker, flying for Team Oracle, practices aerobatics above Puget Sound near Seattle, Thursday, Aug. 5, 2010. Tucker was preparing for performances at this weekend’s Seafair air show over Lake Washington in Seattle. (AP Photo/Ted S. Warren)

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Under a canopy of bamboo, Mei Xiang, one of the National Zoo’s pandas, eats a fruit popsicle on a warm summer day in Washington, on Wednesday, July 7, 2010. (AP Photo/Jacquelyn Martin)

Under a canopy of bamboo, Mei Xiang, one of the National Zoo’s pandas, eats a fruit popsicle on a warm summer day in Washington, on Wednesday, July 7, 2010. (AP Photo/Jacquelyn Martin)

Tian Tian, one of the National Zoo’s pandas, wipes his face while eating a fruit popsicle on a warm summer day at the zoo in Washington, on Wednesday, July 7, 2010. (AP Photo/Jacquelyn Martin)

Tian Tian, one of the National Zoo’s pandas, wipes his face while eating a fruit popsicle on a warm summer day at the zoo in Washington, on Wednesday, July 7, 2010. (AP Photo/Jacquelyn Martin)

Fireworks explode over Washington as the United States celebrates its 234th birthday, Sunday, July 4, 2010. Seen from left is the U.S. Capitol, Washington Monument and Lincoln Memorial. (AP Photo/Cliff Owen)

Fireworks explode over Washington as the United States celebrates its 234th birthday, Sunday, July 4, 2010. Seen from left is the U.S. Capitol, Washington Monument and Lincoln Memorial. (AP Photo/Cliff Owen)