WASHINGTON — Jon Stewart is stepping into what’s become a familiar role for him: cajoling Congress and the federal government to do what’s right and, in this case, taking care of soldiers who have gotten sick serving overseas.

The former host of “The Daily Show” has used his star power to pass permanent 9/11 health and compensation legislation, and on Wednesday he tried to get the attention of Congress to support legislation to cover veterans exposed to mountains of burning garbage during deployments in the war on terror.

The smoke from the trash that was incinerated in the open, football-field-sized pits is entirely unfiltered and laden with poisons such as dioxin, benzene, fine particles and numerous elements all too similar to the toxic smoke and dust that sickened 9/11’s first responders.

And just as they’ve dealt with the fallout from the terror attacks — passing comprehensive laws after more than 18 years — neither Congress nor the federal government has acted to aid the 3.5 million current and former warfighters the Veterans Administration believes were exposed to burn pits.

Speaking at a Capitol Hill news conference, Stewart argued that large numbers of veterans are now turning up with breathing problems and cancers, which should have been expected by the federal government, yet the VA currently denies nearly 80% of claims linked to toxic exposures.

“I just want to make sure everybody understands — this is not a surprise to the United States government,” Stewart said, pointing to recent reports that the Department of Defense and the VA had already drawn up lists of illnesses they expected would impact soldiers.

“Attached to that list are all the different toxins that they knew everybody was being exposed to in 2010,” Stewart said. “The EPA has internal documents — ‘this is why we can’t do burn pits in the United States, these are the toxins, this is how it’s going to go.’”

“None of it is a surprise,” Stewart said. “The only thing that hasn’t happened is action. So no more excuses and no more, ‘Jesus, this is the first time we’re hearing about it.’ It’s not. They know this is coming.”

Stewart spoke as members of the House Veterans’ Affairs Committee introduced a package of legislation called the PACT Act, short for Promise to Address Comprehensive Toxics.

Although official cost estimates for the proposed legislation have not been released, sources said they are likely to be cost tens of billions.