The point is that the "how do we pay for it"? seems like a stonewall more than anything else - given the federal govt's notorious habit of spending on frivolous or unnecessary things (such as the Iraq War supposedly justified as "defense" spending), I'm confident we could cut a good chuck of our nonsense spending and easily be able to afford it.
What is "nonsense spending," exactly, and how much does cutting it add up to? And what is the cost of the program you're suggesting? And how much does it grow over time? These aren't stonewalls, these are important questions.
There's a reason people (politicians in particular) use vague references like "wasteful programs" and "cleaning up inefficiencies" to explain how they'll pay for things: because they're non-specific. It allows them to promise programs without having to justify new spending, even though the cost is virtually never offset by these marginal changes.
You're not paying for new entitlements by trimming fat. The math just isn't there.