How did I get to be almost 40 years old and I have never heard the expression "hanging fire" with respect to bills in congress close to the end of a term... I have to assume that this is a common expression -- not less than 5 times in the last 2 hours have I heard someone on NPR (including Lehrer newshour, Marketplace, and All Things Considered) use the phrase...I found it rather difficult to get a good definition and history of the phrase searching the web via Google, but came across a number of interesting things along the way. The most succint was Allwords:
Idiom: hang fire
To delay taking action.
Thesaurus: delay, procrastinate, stall, stop, vacillate, wait, hang back; Antonym: press on.
To cease to develop or progress.
Hang fire with the polysyllabicsFANS of plain English are not always fans of thesauruses, because they can prompt novice writers to use needless polysyllabics. But they do have their uses (that's the thesauruses, not the fans of plain English . . . no, hang on, they have their uses too).
Reader Terry Carroll (firstname.lastname@example.org) had been having trouble finding a definition of the phrase hang fire: "I'm unable to find it in a dictionary," he writes, "but from context, I gather that it refers to a project that has been postponed through procrastination. But why hang fire?" Smaller (meaning household) dictionaries are likely to miss phrases such as this, but a thesaurus gives a clue. It lists hang fire alongside misfire, flash in the pan and fizzle out - all terms relating to gunnery or musketry. When a soldier lit the fuse in a cannon there could be quite a delay until the charge ignited, and this was known as hanging fire. Similarly a flash in the pan related to a failed attempt to fire a flintlock musket, when the flint produced a spark in the priming pan but did not ignite the charge.
And the great sash they wear in many a fold around their waists has two or three absurd old horse-pistols in it that are rusty from eternal disuse-- weapons that would hang fire just about long enough for you to walk out of range, and then burst and blow the Arab's head off.