Republicans and Democrats in the Senate are embroiled in debate over a spending provision in the PACT Act, a bill that would help veterans exposed to toxic burn pits, as the legislation heads to the floor for another vote.

The Promise to Address Comprehensive Toxics Act, known as the PACT Act, has been clouded in controversy centering on a Democratic provision that would allow $400 billion in mandatory spending over 10 years unrelated to veterans.

Last week, the Senate attempted to advance the legislation through a procedural vote, but it landed five votes short of the 60-vote threshold to overcome the filibuster, only receiving 55 votes. Despite the vote coming up short, Senate Majority Leader Chuck Schumer, D-N.Y., said on Thursday that he would bring it up for another procedural vote on Monday. 

An amendment offered by Republican Sen. Pat Toomey, R-Pa., would put parameters on the $400 billion, satisfying GOP concerns and allowing the bill to move forward to final confirmation, say Senate sources. 

BIDEN CONNECTS THROUGH FACETIME WITH VETERANS EXPOSED TO BURN PITS: THERE IS 'SACRED OBLIGATION' TO HELP THEM

Schumer has said that Toomey can bring a vote on his amendment to the floor, but it would require 60 votes to get it across the finish line. The stalled bill comes after it was first approved in June in a 84-14 vote. It maintains support on both sides of the aisle.

With a 50/50 Senate, final passage might also depend on whether all senators are in person for the vote. COVID-19, injuries and other issues have kept the body from meeting with all lawmakers in attendance. Sen. Dick Durbin, D-Ill., is still isolating due to COVID, and Sen. Patrick Leahy, D-Vt., is out until the end of the week since he is recovering from a major surgery.

PACT Act veterans families Capitol

Veterans and their families camped outside of the U.S. Capitol urge the Senate to pass the burn pits, PACT Act. (Kelly Laco/Fox News Digital)

One Republican leadership aide told Fox News Digital that there is a "simple fix" to move the bill forward – remove the "budget gimmick" that would allow the $400 billion in unrelated spending, and transfer it into the "discretionary" spending category while only allowing new spending resulting directly from the bill. 

President Biden's Secretary of Veterans Affairs Denis McDonough claimed over the weekend that Toomey's proposed amendment would force the agency to "ration care for veterans" and put a year cap on spending for veterans still suffering from burn pit injuries.

Toomey took to Twitter Sunday to fire back at the agency, saying that either McDonough is "misinformed" or "willfully dishonest." 

"Nothing in my amendment results in one dime reduction in spending for health care or other benefits for veterans either existent or proposed in the PACT Act," tweeted Toomey Sunday.

"[Secretary McDonough] instead of misinforming the public about my amendment, why don’t you explain to veterans how you already have the authority to cover those with conditions related to toxic exposure if there is sufficient medical evidence but have only rarely done so?"

The failed procedural motion last week came after Sen. Joe Manchin, D-W.Va., reached a deal with Schumer and other Democrats to push forward a greatly revised $700 billion climate change and tax hike bill after previous attempts at pushing through Biden's "Build Back Better" agenda failed.

As a result, Democrats and liberal pundits have blamed Republicans for stalling the PACT Act in retaliation for the new Manchin reconciliation deal.

Sen. Joe Manchin explains new reconciliation bill

FILE - Sen. Joe Manchin, D-W.Va., is met by reporters outside the hearing room where he chairs the Senate Committee on Energy and Natural Resources, at the Capitol in Washington, July 21, 2022. Manchin has been an obstacle for Biden's climate change plans, a reflection of his outsized influence at a time when Democrats hold the narrowest of margins in the U.S. Senate. (AP Photo/J. Scott Applewhite, File) (The Associated Press)

However, a Senate aide told Fox News Digital that an open discussion regarding concerns by Republicans had been raised to Democrats before the Manchin deal was announced, contrary to reporting that the GOP is only dragging their feet now that the reconciliation bill is moving forward.

GOP LABELS MANCHIN BUDGET DEAL AS 'OUT OF TOUCH, MOST RECKLESS' TAX AND SPENDING SPREE

On Sunday, President Biden connected through FaceTime with veterans and their families camping outside the Capitol as they wait for the Senate to extend health benefits for veterans exposed to burn pits during their military service.

Biden, who tested positive for COVID-19 in a "rebound" case after contracting the virus two weeks ago, was originally scheduled to meet with the veterans in person.

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Biden also said that it was "despicable" that there were Senators who opposed the PACT Act, and said he believes that those who opposed the bill were "going to make up for the mistake they made." 

As of Monday morning, the veterans were still stationed in front of the Senate side of the Capitol.

Fox News' Cameron Cawthorne contributed to this report.