I personally have a ton of anecdotal field experience to back that up. I call it the "Philadelphia Model." The advantages gained by the faithful minority party at the spoils table are huge for those on the inside. The ideal national situation for them is a Democrat in the WH, with Republicans holding Congress. That way, they can exact an impressive price for cooperation ... and protect the special interests that pay the personal bills for them and support their re-election efforts. Look that up in your Funk and Wagnalls. You'll see a picture of Mitch MCConnell and that drunkard Boehner.
If you have a Republican representative in Washington, do visit him or her one day. The staffs these people hire in DC are very often Left Wing operatives, who beyond being somewhat better tailored than those shaggy outright loonies who work for Democrats, make no bones about their beliefs.
How do you think Congressman arrive penniless in DC, only to leave 10 years later with net worths of $20 Million or more? The deal with Romney is that the big boys expect him to lose, but have substantial "downticket" impact to get them Congress. E.G., Bush II was defrauded out of Pennsylvania's electoral votes, but Santorum won! That's a perfect scenario in the "Philadelphia Model."
When I was a young conservative I interned for five weeks with a Republican Congressman. I can definitely confirm this statement. I couldn't believe this guy who had a reasonably conservative voting record (nothing to make you jump up and cheer, but respectable) had several liberals working for him. These are the people who are afraid someone like Newt will turn off the spigot again like he did temporarily in the late '90s.