Have congressional Republicans been unpopular before? Yes. Have they been this unpopular? Not in recent memory.
This Gallup chart shows the parties' favorability ratings over the last 21 years, and you'll notice that sharp drop on the right side of the image. That shows GOP support falling off a cliff.
Republicans were deeply unpopular during the impeachment crisis in late 1998, but they're in even worse shape now. Indeed, the angle that surprised me was comparing Republican favorability now to the party's standing the last time GOP lawmakers shut down the government -- they're faring much worse in 2013.
And this is the image showing unfavorable ratings. Note, dislike for Republicans was very strong at the end of the Bush/Cheney era, but once again, it's worse now.
It's obvious from the results that Democrats aren't winning any popularity contests, but you don't need to be a professional pollster to see which party is in better shape.
As for whether there are any practical consequences for poll results like these, I think there are.
The 2014 midterms are still a year away, and the prevailing political winds are bound to change direction -- more than once -- between now and then. What's more, many Republican districts have been shielded from a voter backlash by gerrymandering.
But when one party's public standing reaches a generational low -- as opposed to, say, a minor downturn -- it's bound to have an effect. For one thing, it matters to the parties' recruiting efforts, and there's already some evidence to bolster this point. For another, it affects fundraising, and we've seen anecdotal evidence on this front, too.
What's more, it starts to create a ceiling of sorts. As Republican popularity reaches new depths, it becomes that much more difficult to recover. If the GOP were to somehow add another 10 points to its favorability rating, it'd still be in horrible shape -- and there's nothing to suggest a 10-point boost is on the horizon.
It's far too early for serious speculation about the midterms, but if Republicans are trying to position themselves for major setbacks in the next cycle, they're off to an excellent start.