Curbing the amount of time federal employees are paid for performing union work on the taxpayers' dime is the aim of a bill introduced by a pair of Republican senators.

Sens. Rob Portman of Ohio and Tom Coburn of Oklahoma want to prohibit the current practice, known as "official time" in most circumstances. Official time allows union officials to be released from their regular government duties to perform union work, while still being paid normal wages and benefits.

The practice cost federal taxpayers about $155.6 million in 2011, the most recent year for which figures are available from the Office of Personnel Management. Federal employees spent about 3.4 million hours doing work for labor unions, while drawing full pay and benefits from the government in 2011.

Particularly irksome to the senators are the 188 employees at the Department of Veterans Affairs who are released full-time to do union work. Almost 800,000 veterans seeking disability and pension benefits related to their military service have claims pending at VA. About two-thirds of them have waited longer than 125 days, the agency's self-imposed deadline for processing claims.

"Federal agencies like the VA need to make sure that they have all hands on deck to fulfill their missions," Portman said. "Unfortunately, however, many agencies allow their taxpayer-funded employees to focus their time and energy on full-time political, union activities that don't have anything to do with the official task at hand.

"At a place like the VA, taxpayer dollars should be funding employees to tackle the challenges of the claims backlog and providing necessary medical care to our veterans."

Coburn also slammed the practice in federal law that allows employees to be paid by the taxpayers to do union work.

"Using taxpayer dollars to finance what is often highly partisan and political full-time union work is a grievous violation of the public's trust," Coburn said. "Sadly, this is a widespread problem."

The bill would repeal the existing law that allows union officials to take official time for a variety of reasons, including contract negotiations and employee representation. Official time would still be allowed if both agency managers and union officials agree it is necessary and in the public interest. It would not affect the ability of federal employees to join or organize a union, according to a press release from the senators.

The bill has 12 Senate co-sponsors in addition to Portman and Coburn, all Republicans. A spokesman for the American Federation of Government Employees, which is the federal government's largest employee union, could not be reached for comment.