The Republicans - voters still don't like them!

Commentary By Ron Beasley

Why did the Republicans lose PA-12?  For the same reason they are unlikely to get a knockout punch in November.  A few days I wrote that The popularity of the Republicans is grossly exaggerated.  That also applies to PA-12.  Public Policy Polling

My biggest takeaway from the surprising outcome in PA-12 last night,
besides the fact that Mark Critz and the DCCC did an amazing job?
There's a limit to just how unpopular Republicans can be and still hope
to make gains everywhere this fall.

Barack Obama's mid-30s
approval rating in the district got more ink, but the number that may
have ended up being even more relevant to last night's outcome was the
putrid 22% approval rating for Congressional Republicans with 60%
disapproving of them. Given that our final survey overestimated GOP
performance in the district it's entirely possible that actual support
for the Republican leadership in Washington is under 20%.

Critz
successfully separated voters' feelings about him from their unfavorable
feelings toward his party's standard bearer. The results suggest that
Burns was not successful enough
in separating himself from his unpopular national party.

[bold mine]

Obama is not popular but he beats the Congressional Republicans by double digits.  The Republicans just can't believe they are unpopular so they talk about retaking the House and Senate.  Daniel Larison:

This is a significant problem for Republicans: they continually set
unrealistic expectations of success and naturally cannot meet them, and
then they are forced to explain away the �failure� to achieve the
impossible that they should have never claimed they could achieve. That
doesn�t mean that PA-12 was not a �must-have� win. Just as everything
had to go right for the Democrats to pick up all the seats that they did
in 2006 and 2008, absolutely everything has to go right for the
Republicans to win control of the House, and that includes winning seats
in traditionally Democratic territory when those seats are open and the
district�s voters are strongly against the administration. So far,
that isn�t happening.

It would equally be a mistake to overinterpret a special election
result in a district that Democrats should have won all along, but
special elections should help the party that gains the most advantage
from lower turnout. That party is the Republican Party. These are
elections in which Republican candidates have their best chance to steal
seats that they normally have no business contesting, and they aren�t
getting it done. Antle mentions that the DCCC will not be able to
devote as many resources and people to every competitive race as they
devoted to PA-12, and that�s true, but it�s equally true for the NRCC,
which continues to trail its Democratic counterpart in fundraising and
cash on hand.