Despite fierce opposition from major transit unions, the Senate yesterday gave final approval to the FAA Authorization bill, a five-year extension that removes uncertainty from the FAA, approves a next-generation air traffic monitoring system and, in Harry Reid’s telling, creates hundreds of thousands of jobs. But unions were unhappy about changes to labor law insisted upon by House Republicans, and they expressed betrayal at the hands of Senate Democrats.

The bill avoids the main labor tweak that House Republicans wanted, which would have counted any worker not voting in a union election as a No vote. But it does raise the bar for the number of workers needed to sign cards stating they want to join a union from 35% to 50% of the workforce. Worse, it makes those cards public to the employer, and it weakens the oversight of the lead transit union regulator, the Labor Mediation Board. Eighteen unions with some foot in the transportation sector sent a letter last week protesting these measures in the bill, which was reconciled in a conference committee after almost a year of House-Senate wrangling. But it was to no avail.

The final vote was 75-20, with most of the opposing Senators Democrats. But 37 Democrats supported the bill, including Commerce Committee chair Jay Rockefeller, Majority Leader Harry Reid, and top leadership members Chuck Schumer and Dick Durbin. Here were the 15 Democrats who opposed it:

Akaka (D-HI), Blumenthal (D-CT), Brown (D-OH), Cardin (D-MD), Casey (D-PA), Franken (D-MN), Gillibrand (D-NY), Harkin (D-IA), Klobuchar (D-MN), Leahy (D-VT), McCaskill (D-MO), Merkley (D-OR), Mikulski (D-MD), Sanders (I-VT), Stabenow (D-MI)

The conference report now moves to President Obama, who is expected to sign it. How this will affect the on-again, off-again relationship between Democratas and labor in the Obama era is unclear.