I expect the GOP to lose seats in the House, and gain seats in the Senate, the latter being the branch of the legislature that matters.
Social Security is a much more sensitive issue than tax reform, the latter not even needing selling.
A majority of Republicans support Social Security reform. A majority of Democrats oppose it. Some people seem to have trouble reconciling their opinions with reality.
The Republicans seem a lot less united on major bills to reform of cut government spending than bills to increase it. Remember when House leaders lied to members, fabricated reports, bribed, blackmailed, and basically prostituted themselves freely in order to get the prescription medication bill passed? Not that I'm complaining, except for their hypocrisy, but they seem to be a lot less zealous now.