He pushed back hard. (AP Photo/Andrew Harnik)

WHERE WE ARE RIGHT NOW: Asking what we would lead with today would be like asking if the pope was Catholic. 

"Hours after praying for Mexican migrants who died trying to reach the United States, Pope Francis singled out Donald Trump, telling reporters aboard the papal plane that anybody who wants to build border walls 'is not Christian,'" report Jenna Johnson, Jose A. DelReal and J. Freedom duLac.

"'A person who thinks only about building walls — wherever they may be — and not building bridges, is not Christian,' Francis said Thursday, according to a translation from the Associated Press. 'This is not in the Gospel.'

"'He added: 'I'd just say that this man is not Christian if he said it this way.'"

And so Donald Trump went negative on the pope. Among other responses, he released a statement in which he used the same sort of attacks he's wielded against opponents on the trail:

The pope is wrong: "If and when the Vatican is attacked by ISIS, which as everyone knows is ISIS’s ultimate trophy, I can promise you that the Pope would have only wished and prayed that Donald Trump would have been President because this would not have happened."

The pope has personally stepped over the line: "For a religious leader to question a person’s faith is disgraceful. I am proud to be a Christian... No leader, especially a religious leader, should have the right to question another man’s religion or faith."

The pope is a dupe, who's been outsmarted by Mexicans: "They are using the Pope as a pawn and they should be ashamed of themselves for doing so, especially when so many lives are involved and when illegal immigration is so rampant."

Not pleased with the pope's remarks. (Photo by Jabin Botsford/The Washington Post)

(Odd timing note: today's dustup came shortly after the release of an interview in which Trump said religious leaders should have greater freedom to participate politically and wade into the partisan fray.)  

"As I'm walking up here, they said: 'Mr. Trump, the pope made a statement about you," Trump said at a Kiawah Island, S.C. rally this afternoon. "I said: 'The pope?' I said: 'I like the pope.... Was it good or bad, because if it's good, I like the pope."

It wasn't good, said Trump. "[The pope] actually said it, that maybe I'm not a good Christian or something — it's unbelievable — which is really not a nice thing to say."

Trump's team pushed back as hard as the candidate.

On CNN, Trump supporter Jerry Falwell Jr. said the pope had gone too far -- politics and religion don't mix, he said: “Jesus never intended to give instructions to political leaders on how to run a country."

Of course, this also reminded us of something else Donald Trump has said (repeatedly):

How does all of this play politically? In the shortest of short terms, most of Twitter today seemed to take Glenn Thrush's advice:

On a #TBT note, this tweet was resurrected:

along with this one, from Trump aide Dan Scavino, who'd tweeted the Vatican wall graphic:

The back-and-forth also inspired the return of the #PopeBars meme. 

Some tried to lure Speaker Paul Ryan's office into the feud. Spokesman Brendan Buck just laughed: Not today, Satan.

Moving on to the medium short term -- this weekend -- it's not clear any of this will hurt Trump at all in Saturday's vote. South Carolina is one of the least-Catholic states in the country; if criticizing George W. Bush isn't going to hurt his chances there, criticizing a liberal-sounding foreigner might not be much of a deal-breaker for primary voters either.

(Taking the same "not going there approach: most of the rest of the GOP field. John Kasich gave the most extensive response, mostly avoiding the argument, but heaping praise on the pontiff. "I love the pope," he said.)

The slightly longer short term -- the post-Saturday road ahead -- may not look all that different. More than a few Republicans have...complicated feelings about this pope. (A Post assessment last fall, when Pope Francis visited the United States, found that the presidential candidate he shared the most policy positions with was Bernie Sanders.) The pope may still be deeply conservative on a range of theological issues, but his political comments have obviously hit a liberal note.

Now, in the longest of long terms: If Trump were to be the Republican nominee, his path to victory would probably have to run through industrial and Midwestern swing states at some point. And to claim victory there, he'd have to maintain his strength with white, working-class voters -- which, in those states, very often means Catholic voters.

That vote may not be a monolith, but Trump's quick response today might startle even the most lapsed of Catholics just a touch. Trump's earlier forays into religious tussles drew plenty of attention -- but Muslims only comprise roughly 1 percent of the U.S. population. One in 5 Americans identifies as Catholic.  

(On the other hand: so far this year, nothing has brought Donald Trump down. So you might want to hold off on those Peak Trump thinkpieces for now.)

Nobody knows for sure how much any of this matters, or if it matters at all. What we do know is that @TheTweetofGod sure picked a bad week to retire.

ALSO, OTHER THINGS HAPPENED in the Republican race today. But half the Internet wasn't talking about them (what Nikki Haley endorsement?) so: Trump wins the news cycle, again.

Here's what Marco Rubio might have preferred people talk about: So far this month, some combination of Ben Carson, Marco Rubio, Donald Trump (sometimes, all three) and their teams have accused Ted Cruz, his team and his supporters of, among other things:

sending out last-minute tweets and emails in Iowa to convince Ben Carson voters he was dropping out of the race 

—distributing a flier that looked like an official government form in an effort to trick people into supporting him 

—distributing a flier that managed to anger both Rubio supporters and black leaders

—launching false attack ads

—mounting misinformation robocalls

—being behind a shady Facebook misinformation campaign

—having a campaign manager who was linked to a series of political events that might have played a role in driving a man to suicide

 

And today: Photoshopgate

The Cruz team has consistently downplayed, dismissed or denied the claims completely, saying they're either false, or nothing out of the norm. It's not clear whether South Carolina voters are all that affected by dirty primary season tricks anymore -- or by allegations of tricks. If they don't notice either of those -- and given the week so far, they might not -- that probability's lower than the odds of a blizzard in Charleston.

TRAIL MIX: In South Carolina, Jeb Bush's super PAC has spent nearly as much as the Rubio, Cruz, Carson, and Trump campaigns -- and their super PACs -- combined, according to a Wesleyan University report. 

More attendance headaches for Rubio: Manuel Roig-Franzia has the story of how he secured a spot on a 9/11 committee -- then skipped many of the meetings. 

A reminder from Larry Sabato's team: By March 15, nearly 60 percent of the GOP delegates will have been apportioned.

Donald Trump has finally met a poll he doesn't like: the national survey released yesterday that had him trailing (slightly) for the first time in four months.

It wasn't all fear and loathing on the campaign trail today: Here's Kasich, in an emotional moment at a town hall this afternoon. Watch it here. (VIDEO) 

BY THE NUMBERS: THE LATEST SOUTH CAROLINA POLLS

GOP: Fox News
Trump 32 
Cruz 19
Rubio 15
Bush 9
Carson 9
Kasich 6

margin of error +/- 3.5 percent

DEMS: Monmouth University
Clinton 59
Sanders 30

margin of error: +/- 4.9 percent

MORE NUMBERS:

Big delegate gains. (Photo by Melina Mara/The Washington Post)

HOW HILLARY CLINTON WON THE WEEK SO FAR: There haven't been any primary votes over the past week, but Hillary Clinton still drew 87 delegates closer to the nomination, as dozens of additional superdelegates revealed their support. The new Bernie Sanders superdelegate total over the same period: 11. The current overall delegate count, according to the Associated Press: 481 for Clinton to 55 for Sanders.

If the superdelegate endorsements continued at this pace, Sanders wouldn't just have to score wins in most of the upcoming races just to catch up -- as AP notes, he'd have to deliver landslides. And so we're seeing the return of the superdelegate lobbying campaign....the hard sell.

Before anyone braces for the mother of all convention floor fights, there are probably a few things worth remembering: the first and most important being that even though this year feels as though it should be half over by now, there have only been two (2) actual primary season votes so far. As of today, the overall delegate count bears little resemblance to the popular vote totals. That may not be the case a month from today.

The bigger concern for the Sanders team right now is whether they have gotten any closer to figuring out how to eat into Clinton's support among black and Hispanic voters on the trail ahead. That's why both candidates have been courting Al Sharpton, though Vanessa Williams notes that the question may be less whether Sharpton will endorse than whether -- in a year when big endorsements have so far failed to register at the polls -- that endorsement even matters. (The biggest beneficiary of Sharpton's unofficial Obama endorsement in 2008, she says, may well have been Sharpton himself.)

Late-breaking news today of an endorsement that could matter to some voters on Saturday: Rep. Jim Clyburn (D-S.C.), who had held off backing Clinton when other Congressional Black Caucus members did earlier this month -- but is reportedly ready to do it now.

A big test ahead. (AP Photo/Jae C. Hong)

MORE TRAIL MIX: Here's a look inside the Bernie Sanders app factory: most of those who labor to create the programs have never actually met IRL. Also backing Sanders: Obama "HOPE" poster creator Shepard Fairey, who has designed a pair of T-shirts for the campaign that feature a decidedly un-hippie design.

(BernieSanders.com)

THE NIGHTLY TRAIL: You want more town halls? You got 'em.

CNN hosts its second town hall in two nights; this one features Trump, Kasich and Bush, and begins at 8 p.m. ET. 

MSNBC will host a forum from Las Vegas featuring Clinton and Sanders starting at 9 p.m. ET.

That event will be preceded by a talk with the candidate-that-could-have-been: Vice President Biden, whose interview with Rachel Maddow airs at 8 p.m. ET on MSNBC. 

WORTHWHILE CANADIAN LIST: This offer has been trending for days...now, in case you're curious, here are some Cape Breton fun facts, which include these (full list here):

"12. Everybody plays guitar. We don't teach it in school or anything. It just worked out that way.

"13. Our potholes are bigger than your potholes.

"14. If you tell people you're from Cape Breton, they will trust you with their first born child, which makes kidnapping very easy.

"15. The highest point in Cape Breton is White Hill Lake. Nobody knows, or cares, about this fact. ..."

YOUR DAILY TRAIL PIT STOP: An oddly hypnotic loop of Donald Trump and Bernie Sanders saying "China," repeatedly, via IJ. (VIDEO)