A dozen House Republicans – including U.S. Rep. Ken Buck of Colorado – are urging House Speaker Nancy Pelosi to reel in federal spending.

The GOP lawmakers want Pelosi to promise to only put bills on the House floor that don’t spend more money than allowed by the Budget Control Act of 2011. They plan to voice their budget cap concerns to the California Democrat in an open letter on Friday.

“We respectfully request that you adhere to the existing spending caps currently in law in order to preserve our ability to defend our nation, protect our seniors, and pass down a strong Republic to the next generation of Americans,” the group wrote in the letter shared with the Washington Examiner.

Even if interest rates remain low, the country’s interest repayments will surpass defense spending in five years, the Republicans – led by Rep. Chip Roy of Texas – claim.

“As you know, our nation recently surpassed $22 trillion in debt. With every hour that passes, we add $100 million to that figure. That is unconscionable. That must end,” they write. “And for those who suggest our entire problem is mandatory spending, Medicare is slated to run out of funds by 2026 and Social Security is slated to run out of funds by 2035.”

Roy has so far been joined by Buck, R-Windsor, as well as Republican Reps. Andy Biggs of Arizona, Ted Budd of North Carolina, Michael Cloud of Texas, Louie Gohmert of Texas, Jody Hice of Georgia, Tom McClintock of California, Mark Meadows of North Carolina, Ralph Norman of South Carolina, Van Taylor of Texas, and Ron Wright of Texas in signing the letter.

House Democrats last month aborted efforts to vote on a measure raising the budget caps after the more liberal wing of the conference would not support it without an increase in domestic spending.