Barro's right that Romney should release his plan. However, if Romney were to win (increasingly unlikely), Dems would instantly flip into the obstinate, do-nothing party. I am not claiming equivalence - the GOP has been obstinate to an unprecedented degree the last few years. However, Dems would certainly raise their demands for being part of a "grand bargain." In the presidential primary, none of the GOP candidates said they would accept 10 dollars in tax cuts if there were even 1 dollar in revenue raised. (Romney's plan already shows he wouldn't keep to that.) The GOP threatened to end unemployment insurance if the Bush tax cuts weren't extended in their entirety. If Romney were to win, and need filibuster proof majorities in the Senate, one can imagine Dems will have some pretty stiff bargaining ideas to win their support. What if Romney has to meet 3 dollars of raised revenue for every dollar in tax cut? What if Dems demand he expand Medicare? Would he be willing? I have my doubts.
So, gridlock is likely to be the rule, regardless of who wins the presidency.