If debates still have the ability to move votes, Romney will get a bounce out of tonight. In market terms, Obama’s lead in the polls “priced in” the expectation that he would dominate the debates, so this strong performance by Romney will likely tighten the race.

All of this said, there are two reasons why for conservatives to keep their exuberance in check. In past elections, it isn’t uncommon for the rusty incumbent to come off lousy in the opening debate. This was the case when Walter Mondale won the first 1984 debate against Ronald Reagan and John Kerry won the first debate against George W. Bush. In both cases, the incumbents recovered in the subsequent debates, and ended up winning the election.

Another reason for caution is that Romney, as part of his efforts to disarm Obama’s criticisms, made a number of policy concessions that could box him in and make it more difficult for him to govern as a limited government conservative if elected. At various times during the debate Romney said that he wasn’t interested in cutting taxes, particularly on the wealthy; that he would cover individuals with pre-existing conditions; that he wouldn’t touch Medicare and Social Security over the next decade and would be willing to give more money to seniors for prescription drugs; and that he’d be open to hiring more teachers.