PS I do think spending cuts and entitlement program reform will be necessary, if not in the manner and time frame proposed by the GOP.
I would certainly start with defense spending as being one of the most inefficient and wasteful, and this coming from someone who does want a strong, efficient defense and military. Social programs and spending are the model of restraint and efficiency as compared to many/most DOD programs. One need only look at the horrendously bloated and problem-ridden F35 program to get a sense of the waste and inefficiency permeating much of the defense establishment.
If we can't reasonably assure our national security on expenditures exceeding the next 10-20 countries COMBINED, then perhaps the answer is not to maintain or, much less, increase spending but rather, to do a very deep review and rethink of how we are approaching our defense and military needs (and what those needs actually are). Conservatives ask of a similarly stringent approach to social programs so why not apply like thinking to defense spending rather than giving the DOD a veritable open wallet.
As for social programs, such things as raising ages of eligibility and applying a very progressive means-testing would be good places to start. However, perhaps best for the Democrats to take a vigorous lead here.