The voters had not yet shown up at the volunteer firehouse for Rep. Steve Southerland II’s first town hall meeting here in Franklin County. Across the way, the Sluggers and Shooting Stars were still practicing on the Little League diamonds.

But the officers who protect this fishing hamlet of 2,158 on Florida’s Panhandle were on alert. Even before Southerland’s staff arrived to set up chairs and a slide projector for Wednesday night’s forum, four sheriff’s deputies were patrolling the empty venue. Two of them wore plain clothes, hoping to blend into the crowd of 50 townsfolk who would eventually stream in. A fifth deputy was escorting the congressman.

There had been no indication that Southerland, a freshman Republican, would be in any danger during his visit. But at the other end of Florida, Rep. Gabrielle Giffords (D-Ariz.) was arriving at Cape Canaveral so she could see her husband off at Friday’s launch of the space shuttle Endeavour.

Giffords’s first public outing since being shot at a constituent meet-and-greet in January served as a fresh reminder to her congressional colleagues — and to the local law enforcement agencies protecting them back home — not to take chances.

For Southerland, that meant not only stationing officers at the firehouse but also arming his staff with concealed weapons.

“We believe that’s just smart,” Southerland said in an interview, adding that he obtained permits for his staff to carry handguns. Several of his Florida aides now come to work armed. “When you’re mixing politics and emotion on both sides, it would be irresponsible for us not to take necessary precautions,” he said.

Since the Tucson shootings, U.S. Capitol Police have urged members of Congress to be more vigilant. Lawmakers’ aides now coordinate public activities in home districts with local law enforcement authorities. There are new protocols for reporting death threats, strange phone calls and suspicious Facebook postings.

And the Secret Service is planning seminars for lawmakers and their staffs on how to assess the security of venues to minimize risk at gatherings.

There is cause for the concern. Between October and March, 53 serious threats against members of Congress were reported, a 13 percent increase from the same six-month period a year earlier, law enforcement authorities said. At the same time, the number of non-criminal cases (such as alarming but not specifically threatening e-mails or phone calls) jumped by 18 percent, to 1,211.

“Unlike a year ago when it was all health care, these threats run the social-economic gamut: health, pay benefits, veterans issues, Medicare,” said Senate Sergeant at Arms Terrance W. Gainer, a member of the Capitol Police Board.

Gainer said federal and local prosecutors have filed more charges this year against suspected perpetrators than in previous years, although he did not have a specific number. He said one reason for the uptick could be that staffs are reporting incidents with more regularity.

“I’m not trying to paint the picture that the sky is falling,” Gainer said. “But we’re in some unique times, and there’s still some unstable folks out there.”

Over the past two weeks, lawmakers have dashed across their districts convening public meetings. In a handful of instances, angry voters have asked House Republicans hostile questions about their support for a 2012 budget plan that would dramatically change Medicare and other government entitlement programs for the poor and elderly.

In Orlando on Tuesday, freshman Rep. Daniel Webster’s town hall meeting “degenerated into bedlam,” according to the Orlando Sentinel. Webster (R) was repeatedly interrupted, and a police officer scolded the audience to act “like grown people.”

In Fort Lauderdale, police reportedly removed two hecklers from a town hall held by Rep. Allen B. West (R).

And in Kenosha, Wis., Rep. Paul Ryan, the architect of the GOP budget, was escorted by police out a back door and in a separate car to dodge protesters who had gathered around his vehicle during his town hall meeting. Ryan told TMJ4, a Milwaukee television station, that “loud hecklers” had alarmed police but that it should not be “blown out of proportion.”

The Democratic Party and liberal groups helped organize some of the protests. The scenes were reminiscent of the town hall furor targeting many Democrats in summer 2009 during the health-care debate, although the incidents seem to be far fewer and tamer than before.

The Capitol Police have statutory authority to protect members of Congress anywhere in the nation. Chief Phillip Morse would not discuss specific security measures but said, “We often request the support of our local, state and federal law enforcement partners as needed.”

Last month in Virginia, when members of the 2nd Tuesday Constitution Group appeared at GOP freshman Rep. H. Morgan Griffith’s Christiansburg, Va., office to stage a protest, the local police chief was waiting for them. He asked the activists to fill out an appilication, and they did so without incident.

But afterward, some angry protesters wondered why the congressman’s office had called the police on them.

The answer: because that’s what congressional offices have been told to do since the Giffords shooting.

In some places, securing a congressional event required every police officer on duty. That was the case Monday night in the windsurfing resort town of Hood River, Ore. As Sen. Ron Wyden (D) held a town hall meeting, two Hood River police officers were present.

“That was everybody,” Chief Bruce Ludwig said. One of the officers was a volunteer reservist. If an emergency had occurred elsewhere in town, Ludwig said, they might have had to leave.

Law enforcement officials said the Giffords shooting altered how they prepared for such events in the same fashion that the Columbine High School shootings changed how they respond to reports of trouble at schools.

“You’re always exposed when you’re in public,” Joel E. Norred, second in command at the Franklin County Sheriff’s Department, said as he prepared for Southerland’s visit. “We realize that security is not 100 percent in any situation. You can never guarantee a secure situation. The only thing that security does is it minimizes the risk.”

At the firehouse, Southerland had a testy exchange over the budget with a man seated in the back row. An undercover officer hovered about two feet over the man’s shoulder, his eyes trained on his hands, but the clash did not escalate beyond words.

For the officers standing along the back wall, there wasn’t any more excitement. After an hour and 40 minutes, Southerland said goodbye. And he warned a few people to be vigilant. The road home would be dark, he said, so watch out for deer.

Staff writers David A. Fahrenthold in Oregon and Ben Pershing in Washington contributed to this report.