It takes 2/3 to override a veto -- still unreachable.
However, control of either house could make it impossible to fund the programs involved in implementing the legislation.
Any bill that appropriates money for an Obamacare activity should be DOA.
Thanks for correcting my mistake. If there was a bill to defund existing programs, -14nobama could veto that. But if were new funds (ie, a budget item) the Repubs could leave it out. I suppose that would work.