The first call came in to the U.S. Capitol early in the morning. A Capitol Police officer was too sick to work. Soon, another officer called with the same problem. Then another. And another. By the end of the Columbus Day weekend, more than 70 officers charged with protecting Congress had called in sick.

It was the largest number of Capitol Police officers who ever had "banged in." Many of them say they really were sick -- an illness brought on by fatigue. The continual elevated terror alerts have meant weeks and weeks of 12-hour shifts, little vacation and fewer days off. When Congress decided to stay in session rather than adjourn for the holiday weekend, it was, for many, the last straw.

"The officers are extremely fatigued. They're really stressed out," said U.S. Capitol Police Officer Andy Maybo, chairman of the police union, which did not organize or support the action.

It's not just the Capitol Police. All across the country, but especially in Washington and New York, police officers and federal agents say the heightened alert and the strain of working long hours with no end in sight are taking their toll. Experts on policing, police chiefs and the officers themselves wonder whether the law enforcement agencies can sustain the current staffing levels without a general change in policy by government agencies that would provide some financial and manpower relief.

"It is a real challenge to balance legitimate security needs against the economics of what's possible," said Chuck Wexler, executive director of the Police Executive Research Forum, a Washington-based think tank that helps large police departments. "They have to be more sensitive to the diminishing returns of keeping officers on extended overtime without resting them. Police chiefs are going to have to be more strategic."

The chiefs also have to worry about how to pay their bills. For some, that means asking the federal government to help pay for the vigilance.

"We have been making the case to our congressional leaders that New York, along with Washington, deserves special attention when it comes to federal counterterrorism funding," New York City Police Commissioner Raymond Kelly said Friday in a speech to Army War College students.

Nowhere do the effects of the heightened alerts seem more apparent than in Kelly's city and the Washington area, where law enforcement agencies are spending millions of dollars in overtime and ramping up their counterterrorism efforts in the weeks before the Nov. 2 election. The summer political conventions threat has turned into a general pre-election threat, which is morphing into a threat against January's presidential inauguration, and police officials see no relief ahead.

Law enforcement officials and agency heads said that with the constant alerts, they will do what they have to do to keep the country safe, even when it means canceling annual leave or extending their officers' shifts.

Gary Hankins, president of a Washington consulting firm for police unions, said the result could be more fatigue like what occurred at the Capitol over the Columbus Day weekend.

"The human mind and body were not created to sustain a continuous heightened alert," said Hankins, who headed the D.C. police union for 12 years. "You need to significantly expand the number of people you have performing the services."

Inside the FBI's Washington field office, agents who are already juggling day-to-day threats and intelligence tips also have swung into high gear to plan for the extraordinarily tight security and massive manpower needed for the January inauguration -- the first since the 2001 terror attacks.

"It's rough," said Paul A. Garten, a supervisory special agent of Washington's Joint Terrorism Task Force, which investigates all possible terrorist acts in the District and Virginia.

Three years ago, members of the task force, composed of local and federal law enforcement agencies, had not even finished writing their reports on the Sept. 11 attack on the Pentagon when anthrax was discovered on Capitol Hill. Ever since, they have run out every day to investigate thousands of reports of suspicious packages and powder.

"It seems like right now we're in the middle of a long haul," Garten said. "And it is unrelenting."

Wexler, whose group has studied Israeli counterterrorism techniques, said that although the Israeli police have learned how to stay on heightened alert, this state of vigilance is still "a relatively new phenomenon in this country."

"In Jerusalem, the police get hundreds of bomb calls a day and have been on heightened alert for years," he said. "With alerts that last days and months, every police chief in America is now being faced with a real dilemma with limited resources."

The Capitol Police and other D.C. area police agencies are at the center of that dilemma. On their 12-hour shifts, Capitol officers patrol the grounds, stop cars and trucks at roadblocks and use explosives-sniffing dogs to conduct hundreds of other inspections a day at congressional buildings. At the same time, FBI agents across the Washington region are interviewing Muslim businessmen and activists, Department of Homeland Security agents are stepping up investigations of immigrants and Metro Transit Police officers are patrolling the subway and warning riders to look for suspicious packages and passengers.

Along with the issues of morale and effectiveness are the ballooning costs. In fiscal 2001, New York City spent $200,000 on police overtime for antiterrorism. According to the New York City Independent Budget Office, it costs $500,000 each week to maintain the current terror alert. New York officials said the heightened alert is built into their policing policy and strategy now, but the costs are daunting.

"The city is facing a $3 billion deficit next year, and we are spending money we don't have because Congress hasn't come through for New York," said Ed Skyler, a spokesman for Mayor Michael R. Bloomberg (R).

In Washington, the Capitol Police spend about $1.5 million in overtime every two weeks.

The latest round of 12-hour shifts for the Capitol Police began after Homeland Security Secretary Tom Ridge raised the alert level in August for financial institutions in New York, Washington and Newark. Capitol Police Chief Terrance W. Gainer closed streets on Capitol Hill to protect lawmakers and staff members from a possible truck or car bomb. He set up a dozen checkpoints to inspect vehicles. And he ordered the officers in his approximately 1,600-member department to cancel their leave and begin the longer shifts. Many have had to work six-day weeks, but Gainer, who has received high marks from his officers, is now trying to give most of them two days off each week, Maybo said.

Last month, Gainer ordered many of his officers to begin wearing new equipment to protect them from a biological or chemical attack.

"We truly ask a lot of these guys," Gainer said. "Be sharp, give directions, smile all the time they're doing it and be ready to fall on a hand grenade."

Gainer recently brought his officers together for an intelligence briefing and a pep talk about their role in the nation's safety.

"The days and nights are long, but I told them they are not nearly as long and hot and dangerous as for our countrymen serving in Afghanistan and Iraq," Gainer said.

"The nation is at war. We have a piece of it, and we have to grin and bear our portion."

But on the holiday weekend, a large group of officers decided they had borne enough.

"I was disappointed," Gainer said. "I know that holiday weekend everyone was prepared for less work, but it was disconcerting that an inordinate number did not come in."

U.S. Park Police officers also are weary from constantly working longer shifts under the heightened terrorism alerts, officers said.

Park Police officers, charged with protecting the nation's monuments on and around the Mall, or what they call the icons, also have worked 12-hour days. Park Police Officer Jim Austen said the officers are starting to get some relief in their schedules but are "burned out."

Each police chief is handling the heightened alerts differently. D.C. Police Chief Charles H. Ramsey put his officers on 12-hour shifts with no days off for several weeks right after Sept. 11, 2001. But he said recent intelligence briefings have not convinced him that he needs the longer shifts and reduced time off.

Ramsey said that if the intelligence becomes more specific and imminent, he won't hesitate to take the same steps as the Capitol Police.

"I'll go to 12 hours or longer than that in a heartbeat if I have to," Ramsey said. "We'll cancel days off or leave. We'll do whatever we have to. This is the new normal."

At the same time, Ramsey said, big-city police departments are struggling to strike a balance between responding to terrorism and protecting the public from other social ills.

"I deal with day-to-day crime in addition to terrorist threat," Ramsey said. "I've got to be able to do both."

With a constant barrage of new intelligence from the CIA and other sources, though, sustainability has become the watchword.

"This is a threat with no end in sight," Wexler said.

Staff writers Michael Powell and Michelle Garcia in New York and Mary Beth Sheridan in Washington contributed to this report.

U.S. Capitol Police check drivers for identification and parking permits near the Capitol soon after Washington was placed on higher alert in August.Officers staff the barricades at Maryland Avenue and Second Street NE.