If the President is presented with a bill that would not safeguard the ability of railroad and airline workers to decide whether or not they would be represented by a union based upon a majority of the ballots cast in an election or that would degrade safe and efficient air traffic, his senior advisers would recommend that he veto the bill.
There's a bit of wiggle room in there. When the White House announced its opposition to the House's six-month spending plan, for instance, it was with a direct assertion that President Obama would veto it. But it's a strong statement nonetheless.
The House version of the legislation in question, which would reauthorize FAA programs, contains the anti-union provision. The Senate's version does not. Several House Republicans support stripping the measure from their bill. But House leadership, in concert with Delta Airlines and other anti-union advocates, have been pressing their members to toe party line and leave the language in place.
If they do, it would either have to be removed when the House and Senate resolve their differences in a conference committee, or face a veto.
Needless to say, union advocates are thrilled by the development.