On Wednesday, Pope Francis suffused Washington with what Catholics would call grace and what everyone else - for the crowds aren't just believers - would call pure, almost child-like happiness. This is what goodness looks like.

But for some, the happy vibes carry more than a tinge of unease.

That's especially true for Republicans with a shot at becoming president, such as Marco Rubio.

InteractiveYour messages to the popeMore CoverageCommentary, analysis about Pope FrancisCartoonsCartoons about Pope Francis

The Florida senator has a pope problem. While it seems almost everyone is in thrall to the visiting pontiff, many in the Republican base dislike much of what he has to say: climate change and poverty deniers reject his encyclical on degrading the planet or his call to help the poor; hawks can't abide papal advice to make love, not war; immigration hardliners find him too soft, the list goes on.

What's a Catholic politician such as Rubio to do when the Pope, with sky-high approval ratings (91 percent) meddles in his business? My God, he's questioned unfettered capitalism and the worship of wealth. And on this crystal clear fall day in Washington, the "son of an immigrant family" said we should welcome those who want to come to the U.S. Such effrontery. With Republicans watching from lawn chairs, he said that those at the top of the economic heap have a duty to fight climate change on behalf of the millions left behind by the global economic system. "Climate change is a problem which can no longer be left to a future generation," he said. Before he leaves, he could very well call for raising taxes.

These are uncharted waters for Republicans. The Catholic Church, unlike evangelical Protestants or Jews, largely avoids litmus tests for politicians, except in a few famous cases. John F. Kennedy had to promise he would not be answering to the Vatican. When he ran for president in 2004, John Kerry was warned by bishops that he might be denied communion because of his position on abortion. Like other prominent Democrats, including House Democratic Leader Nancy Pelosi and Vice President Joe Biden, Kerry earned the epithet "cafeteria Catholic." So what should we call Rubio as he squirms his way around the authority of Pope Francis, picking and choosing what to follow and what to reject: an a la carte Catholic? On Sunday, the senator was the guest of ABC's "This Week." The anchor, George Stephanopolous, brought up that Rush Limbaugh has suggested the pope is a Marxist. Rubio dodged and proceeded to explain how he can be a practicing Catholic and take positions diametrically opposed to the pope's.

advertisement | advertise on newsday

Demonstrating a powerful command of Jesuitical casuistry, Rubio explained that he honored Francis' religious authority, but only when the pontiff was on the same wavelength as Republican primary voters.

"He's the spiritual head of the church, who has authority to speak on matters, doctrinal matters and theological matters. And I follow him 100 percent on those issues," he said. But, he added, "The pope, as an individual, an important figure in the world, also has political opinions. And those, of course, we are free to disagree with." So when it comes to the "social teachings, essential issues, like the sanctity of life and things of this nature," Rubio believes the pope's words are "binding and I believe strongly in them." Check. On the other hand, he said he feels free to disregard Francis when he "obviously opines" about what "we should be doing with the climate or things of this nature, on the economics." The pope has made clear that's not the way he sees it. To ensure no one could ignore that this was indeed a "theological matter," he took the trouble to record his views in an encyclical that described climate change as "one of the principal challenges facing humanity in our day" brought about by the heedless pursuit of profit.

There's no mistaking how he feels about our duty to help the poor, either. This is a matter of basic doctrine brought to the fore by Francis in his plain shoes, small apartment, and low cost, low carbon footprint Fiat.

You can feel Rubio's pain. Of all the gin joints in all the world, why did the pope have to walk into his, just as Rubio is finally getting some traction in the primary race. The non-establishment candidates are fading, his star is rising, Trump is off his back and now the pope is breathing down his neck.

Where is Francis's pragmatism, his understanding, his sympathy for those operating in the real world of the Iowa caucuses, where worry about the poor takes a backseat to the defense of corporate farms that are being persecuted for leaking a little waste runoff into the state's lakes.

Knowing that a beloved pope's visit would expose the gap between his doctrine and that of Republicans, the caucus brought in Catholic journalists and thinkers to tell lawmakers how to bridge the chasm. Some didn't get the message. Rep. Paul Gosar, an Arizona Republican, said he'd refuse to show up in the House chamber for the papal speech. "When the Pope chooses to act and talk like a leftist politician, then he can expect to be treated like one." As for Rubio, maybe the pope will persuade him to follow Christ's teachings and not his most conservative followers and donors. Miracles do happen.

Margaret Carlson is a Bloomberg View columnist.