On the campaign trail there is no room for a violater to say "That was out of context" or "This is a nuanced issue". And that's been signed by all but 6 of the GOP House Reps as well as 2 Dem house reps. I don't believe its really been specified but a house rep who wanted out of the pledge could say "I'm out of the pledge after this term" and so long as there was another primary election for them before they opted out I don't think there'd be an accusation of breaking their pledge. Other than that, they'd have to have some really, really good extenuating circumstances or face a powerfully backed primary challenger. This is a written pledge, not some short comment on the campaign trail, most voters would frown strongly on violating something like that and if anything the staunch GOP loyalists who tend to cough up donations and routinely vote in primaries tend to be even more hardcore about violating what would be seen as a written contract. So, every time the democrats try this again with some minor alteration, it's a non-starter and they know it, which is why we accuse them of playing politics rather than making serious suggestions. That is why we keep calling it a non-starter, it requires from the get-go that someone break their word.