It's an interesting contrast: Republicans lost their national majority when they strayed from the principles upon which they were elected. Representative Dawn Pettingill details how Democrats there misrepresented their goals in order to obtain a majority:
Democrats gained the majority in November’s election. They have the Senate, the House and the Governorship. I was told we would govern from the middle, where we had consensus and would be good leaders, working with the other side…for Iowa. That’s how I believe governing should work and what I had worked so hard for.
It did go that way for about a month. Then the special interests, who had given so much money to get House Democrats elected, started wanting their payback.
“Fair Share” came along in early February. We received a bill drafted by some labor lawyers in Washington, D.C. and were told we were passing it, without changes. I and several other Democrats did not go along with it. Although conceptually, I agree that no one should be getting something for nothing, the bill forced everyone who wasn’t union to pay up or be fired within 30 days, public employees would a fair share fee deducted from their pay whether they liked it or not. I filed a change to make it a choice - if the non-union person wanted union services, they could sign up for paying their fair share, if they didn’t sign up, they would not be forced into paying and would not receive union services. That is when the rift began.