Nate Silver studied the campaign websites of Republican and Democratic candidates
for the House in the 33 toss-up districts. He identified the key policy issues on these websites. 

He concludes that Republicans have a clearer, more consistent message. "Pick
us, and we’ll repeal health care, secure the border and reduce the size
of government." On the other side, Democrats have a vaguer platform. They've won health care reform. We're pulling out of Iraq. The candidates aren't sure what the focus for the next election should be. Silver says that the Democrats have been hampered by the broad policy goals put forth by Obama.

I'm not sure why he focused only on the toss-up elections. If he examined all candidates running for office, he would have had a bigger sample. I'm also not sure that candidate websites are the best way to analyze a candidate's platform. Politicians' websites are often bland and boring and filled with useless information. 

That said, this is still a VERY INTERESTING chart, and Silver puts forth interesting conclusions. Why are the Dems talking about Veteran Affairs more than the Republicans? Why are only 72 percent of Dems talking about jobs? Is it a good idea for Republican to make an anti-health care message so
central to their platform? (They are clearly pushing other policies, but
nearly all of them think health care is important. I'm assuming that he has coded "health care" to mean a repeal of Obama's program. I think the public has moved
on, but whatever.)