Congressional leaders remain far from a deal to avoid the deep automatic spending cuts set for March 1, but the consequences of the sequester are becoming increasingly clear with a growing number of agencies issuing warnings about the potential effects.

Secretary of State John F. Kerry on Thursday became the latest high-level official to caution against the cuts, saying in a letter to the chair of the Senate appropriations committee that the reductions would “seriously impair our ability to execute our vital missions of national security, diplomacy, and development.”

Kerry said the sequester would mean $2.6 billion less for State Department programs, including humanitarian aid, military assistance to U.S. allies and security for the nation’s diplomats and facilities abroad.

Department of Homeland Security Secretary Janet Napolitano joined the chorus of cautioners on Thursday, saying the cuts would roll back border security, increase wait times at ports of entry and airports and require furloughs of up to 14 days for law enforcement personnel, among other consequences.

“Put simply, the automatic budget reduction mandated by sequestration would be destructive to our nation’s security and to our economy,” Napolitano said during testimony before the House Homeland Security Committee. “It would negatively affect the mission readiness and capabilities of the men and women on the front lines.”

The union that represents U.S. Customs and Border Protection personnel issued a statement on Wednesday calling on Congress to “immediately put an end to this destructive policy” of sequestration.

National Treasury Employees Union President Colleen M. Kelley said the cuts for Homeland Security would “have a ripple effect throughout the government, since Customs and Border Protection is the second-largest generator of federal revenue, behind only the Internal Revenue Service.”

Kelley said furloughs for DHS personnel would increase wait times at ports of entry by nearly two hours, ultimately affecting the national economy. She pointed to a 2008 Commerce Department report that said border delays at that point were expected to cost the economy $86 billion by 2017 in the form of lost jobs, wages, economic output and tax revenue.

Democrats on the House Appropriations Committee released an assessment of the sequester on Wednesday, saying the reductions would affect everything from military readiness and international affairs to schools and the economy.

The committee estimated that the required budget slashing could cut economic growth in half for 2013, trim medical research funding by $1.6 billion, reduce education funding for at-risk students by $750 million and erase $168 million in funding to protect diplomatic personnel.

The White House released similar estimates on the “most damaging effects” of a sequester. In its “fact sheet,” the administration blamed congressional Republicans for the impasse blocking an alternative deficit-reduction deal, saying many within the party have not compromised on ending special tax benefits for the wealthy.

The GOP leadership continued its opposition to tax increases after President Obama’s State of the Union speech on Tuesday. Sen. Marco Rubio (Fla.) said in the Republican rebuttal: “The idea that more taxes and more government spending is the best way to help hardworking middle-class taxpayers — that’s an old idea that’s failed every time it’s been tried.”

On Tuesday, Deputy Defense Secretary Ashton Carter said sequestration would threaten national defense at a dangerous time. “The wolf is at the door,” he told the Senate Armed Services Committee, noting that the automatic cuts would eliminate $46 billion from the Pentagon budget over the next seven months and require furloughs for the defense civilian workforce.

Carter added on Wednesday that about 40 percent of the approximately 800,000 Defense Department employees facing furloughs are veterans.

Already, the Pentagon has taken steps to trim spending in preparation for the possible sequester, including implementing a hiring freeze and slashing operating costs on military bases.

Army Chief of Staff Gen. Raymond Odierno said Tuesday: “I began my career in a hollow Army. I don’t want to end my career in a hollow Army.”