NEW ORLEANS -- The White House released its latest pandemic flu plan on Wednesday and it paints a scary picture.

Officials are bracing for a possible bird flu outbreak that at its worst could kill 2 million Americans.

The White House plan said a flu pandemic could lead to "high levels of illness, death, social disruption and economic loss." The plan released on Wednesday is the latest step in government preparations.

According to the White House plan, schools could be shut down, stores closed, mass transit halted and troops could enforce quarantines if the deadly bird flu becomes contagious in people and arrives in the United States.

"The whole purpose of planning and preparation is to mitigate the uncertainty, to take the fear out of it so there's not chaos,” said Fran Townsend, the White House homeland security advisor.

Townsend said a pandemic would probably start overseas.

Among other things, screening of travelers to the U.S. could help stall an outbreak here and buy some time for people to get vaccinated and give health officials time to prepare.

But officials predict it would be impossible to stop the disease from ultimately reaching the U.S.

So they're telling federal agencies to create plans to stay up and running and asking businesses to brace for absentee rates of up to 40 percent. Employees who do come in to work should stay 3 feet apart and communities should make flu preparations a priority because officials say federal help will be limited.

Meantime, some critics said first responders get too little help from the administration already.

"People back home in a local community are really defenseless unless we are going to have national federal leadership and that's what we are calling for. We haven’t had it to date,” said democratic Sen. Edward Kennedy, D-Mass.

But the White House denies being behind the curve. Officials in the nation's capital said this is just the latest step in extensive planning that is already under way.

One thing administration officials said they would not do is close U.S. borders. Officials said they believe don’t believe it would stop the disease from spreading and would cause too much damage to the U.S. economy.

If there were a flu pandemic here in the U.S. how long would it be expected to last?

The White House plan said that nationally there could be multiple waves of illness lasting two or three months each and the outbreak in any one community would probably last about six to eight weeks. They also said outbreaks might not be limited to the traditional flu season.