I think it’s pretty clear that whatever Senate Dems do, Gorsuch will be confirmed. His appointment will be clouded by Republicans’ unprecedented obstruction of Obama’s nominee. Unanimous abstention on the part of Senate Democrats would, I think, point out the historic attack on the checks and balances of our democracy in ways that simple No votes would not.
Such an act would say: we know what you’re doing. We can’t do anything about it. You have broken our centuries-old traditions and systems, and we mark it by sitting this one out.