I'd call it politics of self-interest rather than politics of national interest. These actions were perfectly logical and reasonable, if your goal is to improve the position of your party potentially at the expense of the nation.
Well the point was that in a different political system such actions would not improve the position of your party. The idea that is does seemed odd to me and the only possible explanation I could come up with was that apparently enough people seem to dislike the Democrats so much that they would support such non constructive behaviour.
It's more that people just don't pay attention to the details and put far too much emphasis on the power of the President. President makes promises, fails to fulfill many of them, then the President and his party takes a hit. It doesn't matter that the reason they were blocked is because of action by the competing party.