If President Obama is re-elected, health care coverage will expand dramatically, taxes on the wealthy will go up and Wall Street will face tougher regulation. If Mitt Romney wins instead, health coverage will shrink substantially, taxes on the wealthy will fall to levels not seen in 80 years and financial regulation will be rolled back.

Given the starkness of this difference, you might have expected to see people from both sides of the political divide urging voters to cast their ballots based on the issues. Lately, however, I’ve seen a growing number of Romney supporters making a quite different argument. Vote for Mr. Romney, they say, because if he loses, Republicans will destroy the economy.

O.K., they don’t quite put it that way. The argument is phrased in terms of “partisan gridlock,” as if both parties were equally extreme. But they aren’t. This is, in reality, all about appeasing the hard men of the Republican Party.

If you want an example of what I’m talking about, consider the remarkable — in a bad way — editorial in which The Des Moines Register endorsed Mr. Romney. The paper acknowledged that Mr. Obama’s signature economic policy, the 2009 stimulus, was the right thing to do. It also acknowledged that Mr. Obama tried hard to reach out across the partisan divide, but was rebuffed.

Yet it endorsed his opponent anyway, offering some half-hearted support for Romneynomics, but mainly asserting that Mr. Romney would be able to work with Democrats in a way that Mr. Obama has not been able to work with Republicans. Why? Well, the paper claims — as many of those making this argument do — that, in office, Mr. Romney would be far more centrist than anything he has said in the campaign would indicate. (And the notion that he has been lying all along is supposed to be a point in his favor?) But mostly it just takes it for granted that Democrats would be more reasonable.

Is this a good argument?

The starting point for many “vote for Romney or else” statements is the notion that a re-elected President Obama wouldn’t be able to accomplish anything in his second term. What this misses is the fact that he has already accomplished a great deal, in the form of health reform and financial reform — reforms that will go into effect if, and only if, he is re-elected.

But would Mr. Obama be able to negotiate a Grand Bargain on the budget? Probably not — but so what? America isn’t facing any kind of short-run fiscal crisis, except in the fevered imagination of a few Beltway insiders. If you’re worried about the long-run imbalance between spending and revenue, well, that’s an issue that will have to be resolved eventually, but not right away. Furthermore, I’d argue that any alleged Grand Bargain would be worthless as long as the G.O.P. remained as extreme as it is, because the next Republican president, following the lead of George W. Bush, would just squander the gains on tax cuts and unfunded wars.

So we shouldn’t worry about the ability of a re-elected Obama to get things done. On the other hand, it’s reasonable to worry that Republicans will do their best to make America ungovernable during a second Obama term. After all, they have been doing that ever since Mr. Obama took office.

During the first two years of Mr. Obama’s presidency, when Democrats controlled both houses of Congress, Republicans offered scorched-earth opposition to anything and everything he proposed. Among other things, they engaged in an unprecedented number of filibusters, turning the Senate — for the first time — into a chamber in which nothing can pass without 60 votes.

And, when Republicans took control of the House, they became even more extreme. The 2011 debt ceiling standoff was a first in American history: An opposition party declared itself willing to undermine the full faith and credit of the U.S. government, with incalculable economic effects, unless it got its way. And the looming fight over the “fiscal cliff” is more of the same. Once again, the G.O.P. is threatening to inflict large damage on the economy unless Mr. Obama gives it something — an extension of tax cuts for the wealthy — that it lacks the votes to pass through normal constitutional processes.

Would a Democratic Senate offer equally extreme opposition to a President Romney? No, it wouldn’t. So, yes, there is a case that “partisan gridlock” would be less damaging if Mr. Romney won.

But are we ready to become a country in which “Nice country you got here. Shame if something were to happen to it” becomes a winning political argument? I hope not. By all means, vote for Mr. Romney if you think he offers the better policies. But arguing for Mr. Romney on the grounds that he could get things done veers dangerously close to accepting protection-racket politics, which have no place in American life.