Here’s a bitter irony. Even if the government shuts down today because House Republicans and Senate Democrats can’t agree to delay today’s effective date for portions of the Obamacare Act, it won’t halt the relentless forward march of the controversial health care law.

Even if other government functions must shut down because Congress has not appropriated operating funds, Obamacare has its own dedicated resources that will not be affected by the shutdown.

The House and Senate have adopted resolutions to fund the government for the next two to three months until the next big showdown, over the debt ceiling, is resolved. But the Democratic Senate opposes the Republican House demand that Obamacare be delayed for one year. Republicans don’t have the Senate votes needed to sustain the House position.

Meanwhile, Congress has not passed a single appropriations bill, although it has had more than eight months to perform this annual responsibility. The Senate, led by Democratic Majority Leader Harry Reid of Nevada, hasn’t approved the budget bills that the House has passed.

If a shutdown occurs over Obamacare, neither side will be blameless.

A wiser course for Republican legislators would be to drop insistence on a delay and let Obamacare determine its own fate, without the distraction of a federal shutdown. The complex system has serious problems.

The administration has already granted over 1,200 waivers from Obamacare to organizations ranging from businesses to unions to members of Congress and their staffs. It has also postponed for one year, on dubious legal authority, the requirement that all firms with 50 full-time employees offer government-mandated health insurance to their employees or pay a big fine.

A number of large firms have already cut employee hours below 120 a month, the government standard for full time, so they won’t have to offer them health insurance.

The major parts of Obamacare that take effect today are the mandate that individuals must buy health insurance or pay a fine, and the creation of a network of insurance exchanges to make sure policies are available.

The mandate’s objective is to make people who don’t want insurance — say, because they are young and healthy — buy a policy through one of the law’s insurance exchanges. The government is offering substantial subsidies to low-income individuals.

If a sizeable number of individuals choose to pay the fine rather than expose themselves to the much higher cost of a government-mandated insurance plan, the Obamacare insurance system could lack sufficient revenues to cover its costs.

Another point of weakness is the complex computer system needed to operate the exchanges and its questionable privacy protection.

The argument for a delay is strong, but the president and Sen. Reid refuse to negotiate. Republicans would be wrong to insist on this common-sense approach if it means a government shutdown. Let Obamacare fall of its own weight.

The main victims of a shutdown will be government workers who go without a paycheck and citizens who rely on their services. About half the government civilian workforce will be furloughed, while the other half will be kept on to perform necessary services. Workers in critical areas of national security, law and order, and administration of major government services to the elderly, veterans and others must keep on working.

But rules for what is stopped and what is kept running in a government shutdown are a handy tool for identifying essential government services. The Departments of Education, Labor, and Housing and Urban Development, and agencies like the Securities and Exchange Commission will be left with skeleton staffs of a few hundred workers each. So will the White House.

The most damaging aspect of a government shutdown is the demonstration that Congress is incapable of performing its fundamental duties. A shutdown inevitably reduces respect for the legislative branch and, if the president is seen as a contributory factor, for the White House. It is depressing to think that members of Congress have drifted so far from reason that they are willing to let the system grind to a halt or stop paying the government’s bills.