E is missing the point. Republicans want to shut down Obamacare because Obama is breaking the law that he passed. He cannot arbitrarily decide to postpone certain parts of this law because he knows it sucks.
Some are disciplined and some are not as some vote along party lines; others vote by special interest groups' and/or lobbyists' suggestions. Lobbyist pay for their vote. Sad to say they vote for what they are paid by lobbyists to do instead of voting for the best interests of the American public. The Republican House majority have adhered to their party's platform by shutting down the government because they want Obamacare shut down. They also adhered by voting against Obamacare over 40 times. This adherence to their party's platform is ridiculous and costly and this adherence has hurt their popularity and puts their re-election in jeopardy. They have also adhered by not voting on their own extravagant spending, but instead voted to cut many needed programs for the poor and middle class.
As far as campaign promises for some that is all they are--promises. Some have adhered to their promises, but others used their promises in order to get elected then did not fulfill what they promised. In other words, they think, "I'm elected now so I don't have to do anything I promised." For example, I believe it was Ryan (you need to double check or say one Congressman) who promised teachers that he would help them if elected, but did an about face when elected and voted against them. Hope this helps; but I'm not sure if this is what you need.
I'm trying to find this answer and I have looked everywhere in my text and can not find it. I'm bad at the subject as it is lol
"How disciplined are politicians in adhering to their party's platform and their own campaign promises? What explains this?"
If anyone can help me out that would be great! :)