Sen. Josh Hawley, R-Mo., sent a message to his fellow Republicans on Monday, following the passage in the Senate of a massive spending bill Democrats passed through the budget reconciliation process: fight.

After a marathon voting session over the weekend, Democrats approved the "Inflation Reduction Act," which will cost upwards of $400 billion. It is a scaled-back version of the $3 trillion "Build Back Better Act" that President Biden pushed last year.

"I’ll give the Dems this. With a 50/50 Senate & a historically unpopular president, they passed major (terrible) legislation. Lots of it," the Missouri Republican tweeted Monday afternoon. "They came to do something. There’s a lesson there for the GOP. If they get back Congress, they better be willing to fight."

The key elements include extending Affordable Care Act subsidies, a suite of climate-related spending and tax credits, provisions on fossil fuel energy, a 15% minimum corporate tax rate and more.  Every Republican senator opposed the bill, and it took negotiations between Senate Majority Leader Chuck Schumer, D-N.Y., and moderate Sen. Joe Manchin, W.Va., to pass it. Manchin had previously kept his fellow Democrats from passing the Build Back Better Act.

REPUBLICANS SAY DEMOCRATS WILL ‘PAY THE PRICE’ IN MIDTERMS FOR PASSING MASSIVE SPENDING BILL

Despite its name, Republicans such as Sen. Ted Cruz, R-Texas, have warned that the bill will end up increasing inflation. Democratic socialist Sen. Bernie Sanders, I-Vt., referred to it as "so-called ‘inflation reduction’"in remarks on the Senate floor, noting that according to the Congressional Budget Office and others, it will have a "minimal impact" on inflation.

Senator Josh Hawley

Sen. Josh Hawley speaks during a Senate Judiciary Committee hearing on Capitol Hill, Sept. 29, 2021. (Tom Williams-Pool/Getty Images)

While the new bill is not nearly as expensive as Build Back Better, Republican National Commiittee Chairwoman Ronna McDaniel stated that it will cost Democrats dearly at the polls.

CLICK HERE TO GET THE FOX NEWS APP

"Democrats will pay the price in November for raising taxes on families during a recession," McDaniel said in a statement. 

Fox News' Tyler Olson and Bradford Betz contributed to this report.