Any resemblance between the Mitt Romney of recent weeks and the Romney of the primary season isn’t coincidental; it’s an oversight on the part of his managers, who have proven more adept at Etch a Sketching away the Romney of spring than many imagined was possible.

The Romney who showed up for the third presidential debate Monday night was, by design, the challenger as milquetoast. With both candidates fighting hard for women’s votes, Romney was determined to avoid anything remotely bellicose in his approach to foreign affairs and his interactions with President Obama. He extolled Wilsonian ends — championing democracy in the Middle East rather than sticking with pro-American tyrants — while eschewing interventionist means that could put Americans in harm’s way. This was a necessary reassurance to war-weary voters who feared that a Romney presidency would mark a reversion to the Republican interventionist norm, to the avid and unnecessary war-making of George W. Bush and the knee-jerk bellicosity of the last GOP presidential nominee, Sen. John McCain.

In fact, Romney’s foreign policy didn’t sound significantly different from Obama’s on Syria or China — and he actually avoided Libya. His newfound moderation on foreign affairs is of a piece with his turn away from hard-right themes that began just after the Republican convention. His choice of Rep. Paul Ryan, the emerging leader of American libertarian conservatism, as his running mate seemed to foreshadow a campaign centered on the dreams of the radical right — scrapping Medicare, dismantling regulations and the welfare state. It hasn’t turned out that way.

Rather than confront Americans with a macro-shift in policy that they don’t want, Romney has focused on blaming Obama for the state of the economy and promising better times on the basis of the most vacuous, undefined economic policies we’ve seen since — well, since McCain, who had no economic policies to speak of.

This has surely been the more prudent option. The only presidential candidate to frontally challenge the New Deal’s social guarantees was Barry Goldwater, and we know how that turned out. Ronald Reagan, by contrast, campaigned by attacking Jimmy Carter’s stewardship of the economy (and of much else) and didn’t mount a Goldwateresque attack on universal social programs (though he did attack programs targeted to the poor and black). The anti-government proselytizing of the Republican right is all well and good, Romney’s strategists concluded, but even Reagan knew that was no way to win an election.

So what does all this mean for how Romney would govern, should he win? The longer he campaigns, and shifts shapes, the less we can be sure about what he actually believes. We tend, however, to put too much stock in what our elected leaders believe — and not nearly enough in the dominant ideology of their party and political base. George W. Bush, for instance, wanted to reform our immigration policies, but he couldn’t persuade his fellow Republicans in Congress to support a path to legalization for undocumented immigrants. Today’s Republicans, radicalized by a virulently anti-immigrant tea party, would be even less receptive to such policies. To win their support, Romney was the most anti-immigrant candidate in the GOP primary field; today, he’s strategically quiet on immigration matters. Even if Romney has moderated his views — a big if — there’s little basis for believing he can persuade his party to follow suit. So it goes with his policies on Obamacare (a few popular aspects of which he now says he would keep), his shift on the availability of employer-provided contraceptives and more.

While Romney has become a general-election tabula rasa, he sits atop what may be the most radical major political party in American history. Regardless of Milquetoast Mitt’s positions, a government with a Republican president and Republicans in control of the House and Senate would use its budget-reconciliation powers (which enables a Senate majority to sidestep the 60-vote requirement so frequently used to stymie legislation) to defund or repeal not only the health-care guarantees and financial regulations that Obama signed into law but also much of the education funding and regulatory safeguards on which Americans have depended for decades.

The radicals who dominate the Republican Party have entertained Romney’s turn to the center as a necessary electoral expedient. The day after a Romney victory, their blitzkrieg will begin — leaving the moderate Mitt of the general election to historians specializing in short-lived phenomena.