The Biden administration last month asked Congress for special permission to increase spending on Secret Service in the weeks ahead, even if Congress only passes a short-term spending bill to avoid a government shutdown, multiple congressional and administration sources tell CBS News.

The White House Office of Management and Budget submitted a so-called anomaly request to congressional committees in August, before the second apparent assassination attempt on former President Donald Trump, this time, at his golf course in West Palm Beach, Florida.

Short-term spending bills, known as a continuing resolutions or CRs, are used the fund the government at current levels for a brief period until appropriations bills for the entire fiscal year are passed. CRs often contain anomaly provisions for programs or activities that require support that departs from general funding levels, according to the Congressional Research Service.

OMB warned in its request that without some flexibility to ratchet up Secret Service spending soon, "the Secret Service would have insufficient resources to sustain and enhance protective operations."

Congressional staffers say there are increasing concerns about Secret Service's funding levels, and uncertainty over how much additional funding will be needed is part of what's bogged down ongoing negotiations and deliberations over government spending for 2025 on Capitol Hill. Congress has until Oct. 1 to fund the government, risking a partial government shutdown a few weeks before Election Day.

In the short term, OMB said in its request that granting special dispensation to boost Secret Service spending would enable the agency to "sustain current operations and address additional protective and campaign travel, operations, and overtime costs as they arise."

President Biden told reporters at the White House Monday morning that the Secret Service "needs more help." He added, "And I think that Congress should respond to their needs if they in fact need more service people."

The Secret Service has separately notified Congress that it needs more resources to complete its mission. In a letter sent a week ago to a Senate subcommittee from Acting Secret Service Director Ronald Rowe said "increased mission requirements of the Secret Service necessitate additional resources."

The GOP vice chair of the Senate Appropriations Committee, Maine Sen. Susan Collins, told reporters, "If the Secret Service substantiates the need, I cannot imagine Congress not meeting that request."

She said that the Secret Service said after the first attempt on Trump's life in July that inadequate resources "were not a factor." But "given the level of protection that President Trump requires and that we're still protecting other former presidents as we should, and President Biden and Vice President Harris, there are a lot of demands on the Secret Service, particularly in an election year when President Trump is going to be all over the country," Collins added.

Ryan Wesley Routh, the suspect in Sunday's incident, was charged Monday with two firearm offenses in federal court. Routh, 58, was armed with an AK-47-style rifle and was allegedly 300-500 yards away from Trump at Trump International Golf Course when members of the Secret Service detail spotted him and opened fire, according to Palm Beach County Sheriff Ric Bradshaw. Routh, who did not fire his rifle, fled and was detained soon afterward. Trump was unharmed and thanked Secret Service agents and local law enforcement, calling them "absolutely outstanding."

This incident comes barely two months after Trump was shot in the ear during a rally in Butler, Pennsylvania, in mid-July. And Congress and federal agencies are still investigating this incident, which resulted in the death of one rally attendee.

and contributed to this report.