Senate food service workers voted today not to join a Service Employees International Union-affiliated local.

The Workers United Mid-Atlantic Regional Joint Board — the SEIU-affiliated union under which the Senate employees would have been organized — reported to Roll Call that while it could not yet release an official tally, the number of votes needed to certify the union had clearly fallen short.

One hundred and sixteen eligible employees had from 8:30 a.m. to 11:30 a.m. and from 1 p.m. to 4 p.m. to vote by secret ballot in an office space carved out of the main cafeteria in the Dirksen Senate Office Building.

Teresa Engleman, secretary and treasurer of the Regional Joint Board, said the union would consider filing charges with the National Labor Relations Board alleging that Restaurant Associates, the corporation overseeing Senate dining services, engaged in unlawful activities in advance of the vote. The company said no labor law violations took place.

House dining service employees have been unionized almost as long as they have been privatized — since 1986.

The Senate halted in-house management of food services in 2008. That year, the Senate Rules and Administration Committee opted to sign a contract with Restaurant Associates, a private corporate food vendor owned by the Compass Group, which took over food services in the House in 2007.

With legislation needed to make the arrangement final, some Senators temporarily held up the process at the time because of worries that the new contract would not adequately ensure employees retained a host of benefits and workplace rights, including the right to unionize.

The objecting Democratic Senators  — the late Edward Kennedy (Mass.), Barbara Mikulski (Md.), Sherrod Brown (Ohio) and Bob Menendez (N.J.) — finally allowed the bill to move forward with the promise that such rights would be included in the contract language.

But workers decided today that they would be better off without a union.

Union officials have questioned some of Restaurant Associates tactics leading up to the vote, alleging the company issued warnings to employees that they could lose pay and benefits during the collective bargaining period.

Engleman and Regional Joint Board Director Harold Bock have also alleged that corporate representatives were conducting “surveillance” that had a chilling effect on pro-union activities.

Restaurant Associates spokeswoman Gina Zimmer has dismissed such charges.

“An informal meeting was held during … working hours shortly after the petition for election was received to inform the employees of the election,” she said in a statement last week. “Since that meeting, Compass representatives, on occasion, have been available to answer any employee question. No employee has been required to attend any of these subsequent discussions.

“Restaurant Associates believes that all information provided in response to the employees’ questions has been factual and in accord with the law,” she said.

Though Senate Rules and Administration Chairman Charles Schumer (D-N.Y.) has remained largely hands-off through this process, his spokesman, Brian Fallon, said today that the staff will remain attentive to how the union intends to proceed.

“It is important that the workers’ rights be respected all the way up to the election, and we will take any allegations suggesting otherwise very seriously,” Fallon said.