It’s not your imagination. The Republican Party really does seem to have taken leave of its senses.

The House GOP majority has decided that its final act before the summer recess will be to take its 40th vote to repeal all or part of the Patient Protection and Affordable Care Act, popularly known as Obamacare. This time, Republicans will vote to prohibit the Internal Revenue Service from playing any role in implementing the law, which would effectively gut the measure — in some parallel universe.

Like all the previous votes to kill, squelch, strangle, kneecap or otherwise incapacitate Obamacare, this one has zero chance of success in the reality that we inhabit. The inelegantly named Keep the IRS Off Your Health Care Act of 2013 could never make it through the Senate. If somehow it did, President Obama would whip out the veto pen faster than you can say “pre-existing conditions.”

Amazingly, this pointless exercise in the House makes more sense than what Republicans are doing in the Senate. There, Sen. Ted Cruz, R-Texas, and his tea party-backed allies — are threatening to shut down the whole government in order to strip Obamacare of all funding.

Cruz and his fellow chief insurrectionist, Sen. Mike Lee of Utah, want the Senate to refuse to pass a continuing resolution to keep the government operating beyond Sept. 30, when the current fiscal year ends.

The nonpartisan Congressional Research Service issued a report Monday stating that implementation of Obamacare would continue even in the event of a shutdown. But mere facts cannot begin to penetrate Cruz’s carapace of certainty.

“There is a powerful, defeatist approach among Republicans in Washington,” Cruz said in a radio interview this week. “I think they’re beaten down and they’re convinced that we can’t give a fight, and they’re terrified.”

It’s quite a bit more likely that Republicans who oppose Cruz’s nutty idea recall what happens when the party throws a tantrum and refuses to fund the normal and necessary functioning of the government. Cruz contends it is mere “cocktail-chatter wisdom” that the party was damaged by Newt Gingrich’s 1995-96 shutdowns; he claims, incredibly, that the episode was good for the GOP. Veteran Republican legislators who bear scars from that battle — including House Speaker John Boehner — would beg to disagree.

The shut-it-all-down initiative has the support of Sens. Marco Rubio of Florida and Rand Paul of Kentucky, both of whom are thought likely to seek the party’s 2016 presidential nomination — as is Cruz. I think someone should sign them all up for a reality show called “Tea Party ‘Frenemies.'” I’d watch.

This would all be hilarious if it weren’t so alarming. Absent strong leadership from mature adults, the GOP is drifting past “party of no” territory into an uncharted realm where the object seems to be to make the nation ungovernable.

Unable to control his unruly majority, Boehner has essentially given up; judge the House not on how many laws it passes, he said recently, but how many it repeals. Even by that standard, of course, this Congress is strikingly unproductive, since all those votes to repeal Obamacare have done nothing except waste everybody’s time.

At this point, Republicans won’t even support their own ideas. For years, the party has complained that corporate tax rates are so high that they discourage job creation. So what was the reaction when Obama proposed lowering those corporate tax rates? House leaders immediately signaled that they are not interested.

Boehner does seem to be standing firm, at least for now, against the idea of a government shutdown over Obamacare. He has a powerful self-interest in the matter: While Democrats face an uphill struggle to reclaim control of the House in next year’s election, the task becomes easier if voters are angry with Republicans for cutting off government services.

If we get past the shutdown threat, the next opportunity for mayhem will be a GOP threat — yet again — to grievously wound the economy by refusing to raise the statutory debt ceiling. Maybe we’ll make it past this crisis, too. But chances that Republicans will actually let Congress do anything constructive seem dimmer than ever.

Obama can use his executive powers, but those only go so far. Next year voters will have to decide whether elected officials who do not believe in government should perhaps find another line of work.

Eugene Robinson’s e-mail address is eugenerobinson(at)washpost.com.