If anti-labor forces in Washington are nothing else, they are persistent. Yesterday the House of Representatives narrowly passed a Republican amendment to the Department of Homeland Security budget which would prevent thousands of airport screeners from forming a union, a right they won only months ago after a bruising Senate fight.

Employees of the Transportation Security Administration are currently voting in a runoff election to determine whether the American Federation of Government Employees or the National Treasury Employees Union will represent them.

But late Wednesday, Rep. Todd Rokita, a Republican from Indiana, offered an amendment to the Homeland Security bill that would prevent any federal funds from being used for collective bargaining by the TSA, citing national security concerns. “Collective bargaining agreements would hamper the critical nature of TSA agents’ national security responsibilities,” Rokita said on the House floor. “Union demands will unquestionably make our transportation security more costly and less efficient.”

The amendment passed by a narrow 218-205 margin, with 18 Republicans defecting from an otherwise party-line vote. Rokita’s national security rhetoric echoed Republican tactics from a debate in the Senate earlier this year, which narrowly defeated two measures that would have prevented TSA unionization.

AFGE president John Gage told The Nation the union expected the measure would pass, but that he was surprised it was an issue again so soon after having been seemingly resolved in the Senate. “It’s outrageous. It’s already settled,” Gage said. “It doesn’t seem to me that there’s any limit to where some of these people go to restrict worker’s rights, to really go on a rampage against unions.”

Gage was particularly incensed by the national security rhetoric. “It’s an insult to a union members’ patriotism,” he said. “Maybe they don’t realize the people who went up the stairs on 9/11 were union members.”

Terrorism has been the canard of anti-TSA unionization forces since the beginning of the Obama administration. In December 2009, Sen. Jim DeMint placed a hold on President Obama’s nominee to head the TSA, Erroll Southers, as a warning shot against unionization. In a statement about his hold on Southers, DeMint cited the attempted Christmas Day bombing that year as “a perfect example of why the Obama administration should not unionize the TSA.”

Southers eventually withdrew his name from consideration for the job, and the Senate confirmed John Pistole to head the agency. In February of this year, Pistole granted TSA workers the right to unionize. DeMint and Sen. Roger Wicker of Mississippi both introduced bills in the Senate to block the unionization, but both were narrowly defeated.

Gage said his union will lobby the Senate to remove Rokita’s amendment, and if unsuccessful, will urge President Obama not to sign the bill.

Republicans proposed two other anti-worker amendments to the Homeland Security bill, though both were defeated.

Rep. Paul Gosar of Arizona introduced a measure that would have prevented any new construction or other projects undertaken by the Department of Homeland Security from complying with the Davis-Bacon Act, which requires prevailing wages on federal projects. That was defeated 234-183, with the help of 52 Republicans.

Another amendment by Rep. Steve Scalise of Louisiana would have prevented DHS from mandating Project Labor Agreements on construction projects. PLAs require the government to award public construction projects to unionized firms. That was narrowly defeated, 213-207.