As rhetoric over the nation's shortage of flu vaccine intensified on the campaign trail, federal officials announced today that an additional 2.6 million does of flu vaccine will be available in January.

"We've successfully worked through vaccine supply problems in the past and we're doing so this time as well," Health and Human Services Secretary Tommy Thompson said today at a news conference.

In addition to the doses to be supplied by the French company Aventis Pasteur, Thompson said his department is negotiating with a Canadian company for an additional 1.5 million doses. The country will still be short tens of millions of doses this year.

U.S. health officials said the FDA would inspect the Canadian facilities to see if they meet U.S. standards.

Those supplies "give us the ability to stave off the harsh effects of flu this coming season," Thompson said. "We have good reason to be optimistic."

The United States also has enough antiviral drugs available to treat 40 million people who get the flu, he said.

The reason the additional doses are becoming available is that Aventis Pasteur each year holds back a small supply of the virus used to make the vaccine because the production strain generally becomes less able to replicate effectively during the latter stages of manufacture, the company's chairman, David Williams, said.

Williams said the company now calculates that it has enough of the virus for its normal production run and can free up the held-back supply. The company has already ordered enough eggs used to grow the vaccine, but the time required for production means the doses will not be shipped until the first two weeks of January.

The peak season for flu is February and March, he added, so having extra vaccine available in January will be helpful.

Federal authorities are working to distribute what they have to the areas that need it most.

Dr. Julie Gerberding, director of the federal Centers for Disease Control and Prevention, said today the government was "mapping by county across the United States the expected number of high-risk people and number of doses of vaccine that have already been delivered."

The Bush administration has been scurrying to secure vaccine after a British manufacturing plant that had been expected to provide about half of the U.S. supply shut down. British officials said vaccine from Chiron was contaminated.

At the first of three political rallies in western and central Florida today, President Bush thanked "healthy Americans" for foregoing their annual influenza vaccination.

"I know there are some here who are worried about the flu season," Bush told several thousand supporters in a baseball stadium in St. Petersburg, a comment that responded to criticisms voiced in the state Monday by Kerry.

"I want to assure them that our government is doing everything possible to help older Americans and children get their shots, despite the major manufacturing defect that caused this problem."

Kerry campaign officials expressed pleasure that the president appeared to be on the defensive, especially on the flu vaccine issue.

"The president is becoming the Bart Simpson of American politics, (saying), 'It was like this when I got here. I got nothing to do with it,'" Joe Lockhart, a senior Kerry advisor, said today in a conference call for reporters. "And it's just not true."

Times staff writers Matea Gold in Pennsylvania, Maura Reynolds in Florida and Mary MacVean in Los Angeles contributed to this report, as did the Associated Press.