WASHINGTON — As the partial government shutdown enters its fifth week, the funding freeze has impeded F.B.I. efforts to crack down on child trafficking, violent crime and terrorism, according to a report issued Tuesday by the group that represents the bureau’s 13,000 special agents.“The resources available to support the work of F.B.I. agents are currently stretched to the breaking point and are dwindling day by day,” said Thomas O’Connor, the president of the group, the F.B.I. Agents Association.The report reflected the scope and seriousness of the shutdown’s effects, and came as President Trump and the leaders of the two parties on Capitol Hill maneuvered to find a path out of the impasse. The Senate scheduled procedural votes for Thursday on competing Republican and Democratic proposals, although neither appears likely to win sufficient support to pass.The Justice Department, which oversees the F.B.I., is one of the government agencies affected by the partial shutdown, along with the State Department, Transportation Department, Agriculture Department, Interior Department and others.Mr. O’Connor said that national security was directly related to the bureau’s financial security. “It is critical to fund the F.B.I. immediately,” he said.Because of the shutdown, the F.B.I. has been unable to issue grand jury subpoenas and indictments in several cases cited in the report.An agent working on an MS-13 investigation that has gone on for more than three years and resulted in 23 gang indictments for racketeering, murder and money laundering has been hamstrung by his inability to pay for an interpreter who can communicate with his Spanish-speaking informants, the report said.The bureau has also not been able to pay its informants, an important source of intelligence in terrorism, narcotics, gang, illegal firearm and other national security cases. The F.B.I. could lose those informants.“It is not a switch that we can turn on and off,” the report said.The 72-page report described how field offices in some cases have run out of basic supplies like tires for vehicles, copy paper and forensic supplies like DNA swab kits, and do not have the funds to buy replacements.The F.B.I. is not the only part of the Justice Department struggling during the funding lapse. The department has had to ask the federal courts to postpone some major civil litigation, including a lawsuit over the lawfulness of the Affordable Care Act, which the department no longer defends in court.The federal courts that hear Justice Department cases are also running out of money. The nation’s legal system could soon be hobbled if Congress and the Trump administration cannot come to an agreement to reopen the portions of government that have been closed since last month. The federal courts will run out of money by around Feb. 1, requiring them to cut back to essential services at that point and furlough some workers.The F.B.I. Agents Association has been warning of the negative effects of the shutdown for nearly two weeks.On Jan. 10, the association and representatives from all of the F.B.I. field offices signed a petition that said the shutdown could create financial issues for agents that would make it hard for them to pass the routine financial background checks necessary for them to obtain certain security clearances. They also said the pay freeze would make it hard to retain and attract agents.The latest report from the association, which is based on the accounts of scores of agents, outlines more dire consequences. The group allowed the agents to speak anonymously to protect them from retaliation and other negative repercussions.