Congressional tour guides and visitor assistants filed a petition to form a union Friday, taking the initial step toward creating the first union in the guides’ 134 years of existence.

The filing comes more than 18 months after the Capitol Visitor Center opened and the Capitol Guide Service was transferred to the Architect of the Capitol. While about 40 tour guides once worked out of a small operation in the Senate, they are now part of a large agency that employs more than 3,000 people.

That transition has not gone well, according to several tour guides who asked to remain anonymous because the AOC forbids employees to talk to the media. Guides complain of poor management practices, unclear benefits and a “punitive” atmosphere.

Earlier this month, 18 tour guides and visitor assistants wrote a letter to about 30 Members of Congress informing them of their intention to organize a chapter under the American Federation of State, County and Municipal Employees. Three weeks later, they have collected the signatures of more than 50 percent of about 150 tour guides and visitor assistants — significantly more than the 30 percent required by law, according to Carl Goldman, the executive director of AFSCME Council 26.

“We need an advocate who can represent us, because we feel like our interests are not being represented,” said one guide who has given tours for more than a decade. “We need somebody to help promote transparency. … There doesn’t seem to be an open process for doing things.”

AOC spokeswoman Eva Malecki declined to comment on the petition. But filing the petition is just one step in a long process to form a union.

First, the Office of Compliance must confirm that the petition has the required number of signatures and that they are valid. The AOC management, meanwhile, can dispute the proposed bargaining group; for example, officials could argue that employees other than guides and visitor assistants should be included.

If the OOC does approve the petition, union representatives and AOC management would begin negotiations on holding an election that would determine whether employees want to organize. Such planning can take months.

At least one Member has given employees encouragement. After receiving the letter from employees earlier this month, Rep. Gerry Connolly wrote that “unions can improve the quality and efficiency of public service delivery.”

“Since CVC employees are often our visitors’ primary interface with Congress and the federal government, their work is particularly important,” wrote the Virginia Democrat, who is a member of the Oversight and Government Reform subcommittee that handles federal workers issues. “I look forward to working with you to [ensure] that we offer Capitol visitors the best possible experience.”

CVC employees continue to complain about management practices. One tour guide said many employees are afraid to ask questions for fear of being reprimanded. Guides also complain of overpacked theaters, unsanitized headsets and no allotted research time.

Employees were further disillusioned when a CVC supervisor recently decided to throw out a bag of white power labeled “anthrax” without calling police. After carrying the bag through groups of visitors and flushing it down the toilet, the supervisor belatedly called the Capitol Police, who then spent hours making sure the area was safe. The Capitol Police and the Office of Compliance are investigating the incident.

One CVC employee said the system for alerting employees to any potentially dangerous incidents in the CVC is inefficient. Before the CVC opened, tour guides carried pagers and were sent messages alerting them to any suspicious packages or evacuations. Now, they are told of such events over their radios, which they can’t listen to constantly while they speak on tours.

Last week, police responded to a suspicious package at the CVC entrance. But the CVC employee said he wasn’t aware of the incident until he asked several people. Though police respond — and quickly clear — suspicious packages often, knowing the status of such events can help tour guides and visitor assistants prepare if any evacuation is necessary, the employee said.