One might be forgiven for thinking that Democrats suffered their own calamity of popularity during the month of November based on the media coverage. However, that just isn't the case. In a mirror image of Republicans, Democrats suffered a small decline in net favorability, by an average of just three points from October to December in polls from the same pollster. Democratic favorability did, however, decline in the late summer and early fall as well. This leaves Democrats with a net favorability somewhere around 15-25 points greater than Republicans, just like at the beginning of 2013. This is a far better position than Democrats found themselves in at the beginning of 2010, when Democrats had a net favorability only about five points higher than Republicans. Not only that, but the Tea Party is no longer a bright, shiny plaything for the media to gush over; rather, it is about as tarnished as the Republican Party itself.
Data for Democrats, the Democratic Favorability Advantage, the Tea Party, and some comments below the fold.
The graphs above each show measurements of party favorability from different pollsters using different variations of the question "Do you have a favorable or unfavorable view of the Democratic [or Republican, or Tea] Party?" The vast majority of the data can be found at PollingReport.com, with the main exception being Daily Kos polls. The trendlines are Loess regression lines. Data from YouGov/Economist is excluded because the polling just began, new data are released every week, and the polling shows lower favorability than other polls, for both parties. All these factors combined would result in the graphs showing a misleading apparent drop in net favorability for both parties in the past month if the data were included.
Governing is Hard
The first year after winning the presidency is generally tough on the party of the president. This can be seen following the elections of 2000, 2004, 2008, and 2012. This is not true for 1996.
Peaks in favorability are often close to election day. Some of that is related to a post-election spike if the party performs well (see, for instance, Democrats in 2008).
Favorability Advantage and the House
Democratic seat gains in the House are roughly correlated to the Favorability Advantage (green line). That green line probably needs to be above the +10 level for House gains. Anytime it flirts with zero or dips below has been bad news in the past.
It's Not the Obstruction
While obstructing Bush from 2006-2008, Democrats saw their favorability improve. While obstructing Obama from 2010-2012, Republicans saw their favorability decrease. Although I don't recall Speaker Pelosi shutting down the government.
Impeachment Trumps Shutdown
The Gingrich Shutdown of 1995-1996 hurt Republican favorability, but nothing like the impeachment. Still, in both cases recovery was rapid.
What to Watch For
Many election years have seen gains in favorability for both parties, leading to little change in the Democratic Favorability Advantage (green line). At this point, this would be a good thing for Democrats. Democratic Favorability is currently at about the same place it was at the beginning of 2010 and 2012; Republican favorability, of course, is lower than in those years. Watch out for extreme events - such as wars, impeachments, and shutdowns.