A reader writes in to note my description of a Senate transportation amendment as falling "two votes short" today, suggesting that it had in fact been filibustered by the GOP.

The Republicans certainly did block the amendment, but it wasn't a filibuster -- what occurred was a motion to waive budgetary rules to allow for more new spending that isn't offset by cuts. Such a motion is more of a fiscal box-checking than a political obstruction, though it has the same effect in practice. Sixty votes are needed to waive budgetary rules, the same margin needed to break a filibuster.

But If no budgetary motion had been made on the amendment, it likely would have been deemed "non-germane" according to Senate rules -- and fallen short in the end. Such is the mind-numbing tradition of parliamentary procedure.