Ramesh Ponnuru is a Bloomberg View columnist, a visiting fellow at the American Enterprise Institute, a senior editor at National Review, and a leading conservative pundit. The views expressed here are his own.

July 26 (Bloomberg) — Conservatives on Capitol Hill think they have a chance to strike a mortal blow against President Barack Obama’s health care overhaul this fall. If their plan goes forward, however, it will backfire.

The plan is to oppose any bill to fund the government or increase the debt limit that also provides money for putting the health care law in place. Because Republicans control the House, Democrats can’t continue borrowing or paying for government operations without Republican support. So, conservatives say, Republicans should insist on defunding Obamacare as the price of that support.

The chance that Democrats would go along — would give up on their signature legislative initiative of the last decade soon after having won the presidential election and gained Senate and House seats — approaches zero percent. So if Republicans stay firm in this demand, the result will be either a government shutdown or a partial shutdown combined with a debt default.

Either would be highly unpopular, and each party would blame the other. The public, however, would almost certainly blame Republicans, for five reasons.

First, Republicans are less popular than the Democrats and thus all else equal will lose partisan finger-pointing contests. Second, the executive has natural advantages over a group of legislators in a crisis atmosphere. Third, people will be naturally inclined to assume that the more anti-government party must be responsible. Fourth, some Republicans will say that government shutdowns or defaults are just what the country needs, and those quotes will affect the image of all Republicans. And fifth, the news media will surely side with the Democrats.

This is true even though Obamacare is unpopular. Conservatives and moderate Democrats have grown more skeptical of it over time, and 22 House Democrats voted with the Republicans to delay its individual mandate. But none of those Democratic representatives would have a hard time standing against Republicans if they try this maneuver. They’ll just say they oppose a shutdown or a default. Democratic voters who harbor doubts about the health law will take the same view.

Bringing the federal government to a standstill would confirm the Democrats’ caricatures that conservatives are reflexively hostile to all government. And Republicans would be doing it without proposing a plausible replacement for Obamacare. So Democrats would be able to say that Republicans were crippling the government and credit markets in order to take health insurance away from 30 million people.

While Democrats would stay unified, Republicans would fracture as their standing in the polls dropped and negative news coverage continued. When they inevitably lost the fight, they would be more divided, unpopular and demoralized than before, and the cause of repealing Obamacare would look more like the hobbyhorse of incompetent fanatics.

Republicans are right that Obamacare is a very bad law. They urgently need a strategy for scrapping it — and any workable strategy has to include a conservative alternative, something few Republicans have shown much interest in proposing. Trying to defund Obamacare through a budget showdown isn’t so much a strategy as a flight from the responsibility of creating a realistic one.

Republican leaders in Congress, especially Senate Minority Leader Mitch McConnell, are resisting the defunding gambit because they strongly suspect it won’t work. Its advocates say anyone who rejects this tactic doesn’t really oppose Obamacare. That’s an absurd charge. But Republican leaders would be better able to dismiss it if they had their own strategy for replacing the law.

One possible outcome of this debate is that the Republican House passes a government-funding bill that doesn’t include money for Obamacare, but then gives in to the Democratic Senate on the issue. At that point the conservative groups that are pushing for defunding will say Republican leaders have again betrayed them, and get back to the vital work of raising donations off that idea.

That won’t be the happiest of endgames for Republicans, but it would still be better than a shutdown or default that failed to achieve their goals while inflicting political damage on themselves — and, in the case of default, substantial economic damage on everyone else.

The repeal of Obamacare is a worthy and potentially popular cause, but it won’t be accomplished through sheer willpower.

Photo: Gage Skidmore via Flickr.com