Bret Stephens at the Wall Street Journal:

Mitt Romney needed to pass the usual tests for Republican presidential candidates in his debate Monday night with President Obama.

There was the Ford test (alternatively known as the Palin/Cain/Perry test): Would Mr. Romney say something so obviously misinformed, so manifestly silly, so revealingly ignorant as to disqualify him from serious consideration as a prospective commander-in-chief? He said nothing of the sort.

There was the Goldwater test (unfairly named, but reputations are stubborn things): Did Mr. Romney make pronouncements so belligerent as to make ordinary people fear for their children's safety-or at least provide David Axelrod a chance to make it seem as if he did? He did not, though that won't stop Mr. Axelrod from trying.

And there was the Bush test (not unfairly named but mistakenly understood to mean ideology when it ought to be about consistency): Would Mr. Romney find a deft way to define his foreign policy as something other than a retread of the 43rd president-but also as something defensible, distinctive, and (not least) identifiably Republican?

On this score, Mr. Romney succeeded, too, if only in a manner coyly calculated to raise the hackles of every conservative who has harbored doubts all along about the Massachusetts governor.

[...]

Did it matter? I doubt it. There's a case to be made that Mr. Obama has been a disengaged, poll-driven, inconsistent, credulous and cocksure steward of American foreign policy. Mr. Romney didn't seem interested in making it, and as a matter of politics didn't need to make it. His most effective turns in the debate came when he brought it all back to the economy. He seemed reasonable and tempered and pragmatic and unruffled and therefore presidential.

Impressions in politics can be forever. Foreign-policy positions are, as the Romney campaign might say, strictly Etch-a-Sketch.

Stephen succinctly described the key: "Mitt Romney emerges looking like a perfectly plausible president-which was no doubt all he wanted from tonight."

Since the end of September, just before the first debate, Mitt Romney has been surging. As ordinary voters focus more on the election, they appear to have decided to oust Mr. Obama - if Mitt Romney can assure them he is a "plausible" alternative.

It is a psychological barrier that appears to have been broken down by millions of of former Obama supporters. Romney's surge is not in winning undecideds; it is in getting voters to change their allegiance from Obama to him. This is huge and is manifesting itself in key midwestern battleground states like Wisconsin, Michigan, and Pennsylvania. Obama won those states by 14, 16, and 11 respectively. Today, Obama's advantage in each of those states has narrowed considerably, putting 2 of the three in play for Romney. The GOP candidate might not win any of those states, but he is forcing the president to devote resources that could be better utilized elsewhere (Ohio, Virginia) to states he should have already wrapped up.

In his three debates, Romney proved himself at least the equal, and at times the master, of Obama. By any measure, the Obama campaign's attempt to make Romney appear to be a risky choice has utterly failed while the Republican has shown himself to be a viable, plausible alternative.

If the voters want an excuse to kick Obama out, they don't have to look hard to find one.