Updated: 6:53 p.m.

House Administration Chairman Dan Lungren sent a letter Thursday to fellow members of the Republican Study Committee “strongly” urging them to oppose an amendment proposed by the group’s chairman out of concern for security in the Capitol complex.

The amendment to further reduce legislative branch and other spending would have a “dramatic impact on the House’s ability to maintain adequate security and conduct effective oversight,” the California Republican wrote in the letter.

“If adopted, this amendment would severely restrict the U.S. Capitol Police’s ability to secure the Capitol complex,” Lungren added. “A cut of this magnitude would force Capitol Police to face today’s ever-growing security threats with significantly fewer resources and officers.”

The House is debating hundreds of amendments to a continuing resolution that would keep the government funded through the end of fiscal 2011. The amendment by RSC Chairman Jim Jordan (Ohio) would make an across-the-board 11 percent cut to the continuing resolution’s spending on the legislative branch and a 5.5 percent cut to other accounts unrelated to national security.

The move would force appropriators to slice up to $500 million from the legislative branch in addition to the $194 million that would already be removed under the continuing resolution. The amendment is expected to come to a vote on the House floor late Thursday night or Friday, according to a spokesman for House Majority Leader Eric Cantor (R-Va.).

The Capitol Police are the only Congressional support agency not to sustain a budget cut under the continuing resolution. The unamended bill would increase the police budget by $12.5 million over fiscal 2010 to a total of $340 million. That would allow the department to hire seven new agents to track threats against Members.

The deeper cut proposed in Jordan’s amendment would also affect Members’ offices, Lungren wrote. The House already passed a resolution cutting Members’ office budgets by 5 percent, and further reductions would impede lawmakers’ ability to communicate with constituents, he added.

“While I support this effort to reduce federal spending, I fear the wholesale approach proposed in this amendment will render the House and its members incapable of upholding our promise to the American people,” Lungren wrote.

Jordan said Thursday that Congress must lead by example.

“Federal spending has been out of control, leading to record deficits and a massive debt that our children and grandchildren must repay,” he said in a statement. “Our amendment aims to help get federal spending under control, and I believe that when federal spending is reduced, Congress itself must tighten its belt.”