WASHINGTON — Anyone who watched as President Obama explained his health care reform proposals to Congress saw a chief executive making what sounded like a genuine appeal for bipartisanship —and his opponents behaving like a bunch of spoiled first-graders. Obama should ignore them, even if they hold their breath until they turn blue.

House Republicans were particularly ostentatious in showing their disrespect not just for Obama but for the office he holds. The outburst by Rep. Joe Wilson of South Carolina — who shouted “You lie!” when Obama said his plan would not cover illegal immigrants — was only the most egregious display of contempt. Rep. Eric Cantor of Virginia, the House minority whip, fiddled with his BlackBerry while the commander in chief was speaking. Other Republicans made a show of waving copies of their own alleged reform plan, which isn’t really a plan at all.

And Rep. Louis Gohmert of Texas waved hand-lettered signs at the president, as if he thought he were attending one of those made-for-television town-hall meetings rather than a solemn gathering of the nation’s highest elected officials.

Throughout the speech, there was grumbling, mugging and eye-rolling on the Republican side that was not only undignified but frankly un-American. When I was a correspondent in London, I covered far more raucous sessions of the British House of Commons — that’s how Parliament treats the prime minister, who is the head of government. In the United States, that simply is not how Congress treats the president, who is the head of state.

Congress didn’t heckle Lyndon Johnson like that during the Vietnam War or Richard Nixon during the Watergate scandal. Congress didn’t show that kind of bitterness and aggression toward George W. Bush, who did lie — specifically, about the intelligence his administration relied on to justify an unnecessary war that has cost 4,300 American lives and enough money to fund Obama’s health care proposals for a decade.

Wilson issued a statement of apology after the speech, saying he had “let my emotions get the best of me” and calling his interjection “inappropriate and regrettable.” As apologies go, it sounded insincere — a variant of the “mistakes were made” dodge. In fact, however, the right-wing Republicans in Congress, especially those in the House, are all too sincere. And that’s the problem.

Last November’s election so wounded the GOP that the nation is now suffering collateral damage. The Republicans who were punished at the polls for the failures of the Bush years were those in the most evenly contested districts, which meant they tended to be relatively moderate. Those who represent solidly Republican districts were safe, and their greatest fear isn’t being defeated by a Democrat next fall but being challenged by a primary opponent who’s even more of a right-wing yahoo.

There are quite a few Democratic pragmatists in Congress — which is why health care reform is being worked over so thoroughly by the Blue Dogs. In the Republican ranks, especially in the House, pragmatists are few and ideologues are legion. Many of them probably believe the nonsense they spout about creeping socialism and an urgent threat to America As We Know It. But it’s still nonsense. Ideologue sincerity just makes this toxic rhetoric more dangerous.

Obama told those of us who support a public health insurance option that we might have to settle for something less. He threw Republicans a bone on tort reform. And he drew one bright line in the sand: Throw spitballs all you want, but this will be done.