Paul Krugman argues that the far right is pulling out all of the stops to eliminate the ACA because they fear that it might be success. He regards it as just another example of class warfare. Certainly, the far right has been working hard to undo the New Deal since the 1980's. Bush tried to privatize Social Security and he partially privatized Medicare by giving private insurers the opportunity to sell and service Medicare Advantage policies. The ACA is important to the GOP for other reasons as well. In the first place they campaigned against ACA in all of the recent elections. In some districts ACA has been made so unpopular that right wing members of the House have demanded 47 opportunities to put a vote against ACA on the record so that they can use it in their next election campaign. They have been assisted in this effort by a powerful misinformation campaign. The ACA is far from perfect, many would have preferred a single payer system by extending Medicare to everyone. It is modeled after the conservative healthcare plan that was implemented by Mitt Romney. It has been popular in Massachusetts, but increasing benefits to the poor means that a good share of the beneficiaries will be the "wrong kind of people". Some parts of the nation have never forgiven democrats for passing the Civil Rights Act under Lyndon Johnson. At that time Johnson stated that the democrats would lose most of the Southern states and he was correct.
Back in the liberal 1960's many democrats were opposed to Vietnam war and establishment democrats were not willing to end the war. Some democrats considered dropping out of the party and forming a more progressive third party. That idea was rejected by most democrats and it never happened. They decided to work within the Democratic Party to make it more progressive. Its quite possible that some in the Tea Party would like do something similar with the Republican party. They refer to establishment republicans and RINO's, or republicans in name only. In other words, their ideology is the real ideology of the Republican Party. Its quite obvious that senators like Ted Cruz would like to become the leader of the "reformed" GOP.