ObamaCare was largely a ripoff of existing Republican ideas on health care reform. Since that proved unpopular and they had to position themselves in absolute opposition to Obama, the party had to rally against its own health care proposals. That left them with no other ideas to adopt. Combine that with the redefinition of successful health care policy in America to include the number of insured and it leaves them nowhere to go without triggering a backlash, especially since it is largely Republican states and districts that have benefited the most.
After years of screaming about budgets and deficits, while championing tax reduction, they're now faced with the reality of trying to implement their promises. Not only is tax reduction, especially for the wealthy, very unpopular, but they also realize that Trump was elected in large part because of promises to protect the costliest aspects of the welfare state. So, how do you square tax cuts for the wealthy and businesses with not touching Medicare or Social Security, while also not blowing up the deficit? It can't be done. They'll lie about the CBO numbers and try to spin them, but they know that only goes so far.
Where will border wall funding come from without angering the public? Cuts in food stamps and other social welfare provisions? Expect angry constituents. Plus, they see the polling and know that a border wall is not popular. So, make those sacrifices for an unpopular proposal? How is that beneficial?
The Republican agenda has come into conflict with public opinion. It has also come into conflict with CBO budgeting and reality itself. They've relied so heavily on inciting their base, suppressing voter turnout, gerrymandering, and lack of enthusiasm among Democratic voters to win elections. Hell, even their base is against them on many cuts to the welfare state. They've mastered the art of objection and being a powerful opposition party, but their cynical opportunism has painted them into a corner. They can't fulfill what promises they've made without inciting backlash or reveal that their promises were lies all along (i.e. you can't both provide massive tax cuts and protect the two largest entitlement programs).
