President Trump has clearly soured on Defense Secretary Jim Mattis, and top Republicans and Democrats both tell me his departure would be particularly costly for the White House — and a disturbing sign for outsiders.

• A former aide who can read Trump like a book told me: "His tone on Mattis is really striking. ... Will be worth watching whether he's just brushing him back and moving on, or if he launches a sustained effort to get him to quit."
• And if Mattis departs on anything other than the most cordial terms, confirming a successor will be fraught.

But here's something aides may not have told the president: People who know Mattis tell me that he won't stay around to be abused and humiliated like Attorney General Jeff Sessions has.

• If "Mad Dog" Mattis, as Trump calls him, is convinced that the president is shorting his stock, the retired four-star Marine general could leave abruptly.

After recent rumblings of frayed relations with Mattis, Trump's comments on "60 Minutes" last night sent a signal to the world — including allies who depend on the U.S. for their defense — that the Pentagon chief may be a short-timer.

• Based on an early clip from CBS News, we told you yesterday about Trump's devastating remark to correspondent Lesley Stahl that Mattis is "sort of a Democrat, if you wanna know the truth. ... He may leave."

But it turns out there was more:

• Stahl: "Is it true General Mattis said to you, 'The reason for NATO and the reason for all these alliances is to prevent World War III?'"
• Trump: "No, it's not true. ... Frankly, I like General Mattis. I think I know more about it than he does. And I know more about it from the standpoint of fairness, that I can tell you."
• Stahl: "I'm gonna try one more time."
• Trump: "Lesley, you don't have to try again. I know exactly what you're saying. ... I will always be there with NATO, but they have to pay their way. I'm fully in favor of NATO, but I don't wanna be taken advantage of."

Be smart: Mattis is a linchpin of what we call the Committee to Save America —
an unofficial alliance of officials who see it as their patriotic duty to protect Trump and the nation from disaster.

• When I asked a well-wired Democrat how worrisome Mattis' departure would be, he replied: "Number one by far. Super scary."

"Republicans have begun to concede defeat in the evolving fight to preserve the House majority," AP's Steve Peoples writes:

• "[F]rom the Arizona mountains to suburban Denver to the cornfields of Iowa, the GOP's most powerful players this midterm season are actively shifting resources away from vulnerable Republican House candidates deemed too far gone and toward those thought to have a better chance of political survival."
• "Already, ... Republican operatives and spending patterns ... indicate GOP defeat in as many as a dozen House races — halfway to the number Democrats need to seize the House majority. ... Dozens more seats are in play."

"[T]he early Republican-on-Republican blame game has begun":

• "GOP operatives connected to several vulnerable candidates complain that the [National Republican Congressional Committee] has failed to deliver on its promise to invest $62 million in political advertising across 11 states this fall, a promise detailed in a September memo that declared, 'The cavalry is coming.'"
• Corry Bliss, who leads the Congressional Leadership Fund, Speaker Ryan's super PAC, said: "The GOP is now facing a green wave ... Democratic candidates are outspending Republican candidates in key races by $50 million."

"Senator Elizabeth Warren has released a DNA test that provides 'strong evidence' she had a Native American in her family tree dating back 6 to 10 generations," the Boston Globe's Annie Linskey reports.

• "Warren, whose claims to Native American blood have been mocked by President Trump and other Republicans, provided the test results to the Globe ... in an effort to defuse questions about her ancestry."
• "She planned an elaborate rollout [today] of the results as she aimed for widespread attention."

"The analysis of Warren’s DNA was done by Carlos D. Bustamante, a Stanford University professor and expert in the field who won a 2010 MacArthur fellowship, also known as a genius grant."

• "He concluded that 'the vast majority' of Warren’s ancestry is European, but he added that 'the results strongly support the existence of an unadmixed Native American ancestor.'"
• "Bustamante calculated that Warren’s pure Native American ancestor appears in her family tree 'in the range of 6-10 generations ago.'"
• "That timing fits Warren’s family lore, passed down during her Oklahoma upbringing, that her great-great-great-grandmother, O.C. Sarah Smith, was at least partially Native American."

"The inherent imprecision of the six-page DNA analysis could provide fodder for Warren’s critics":

• "If her great-great-great-grandmother was Native American, that puts her at 1/32nd American Indian. But the report includes the possibility that she’s just 1/512th Native American if the ancestor is 10 generations back."

Why it matters: "Undergoing the test and releasing the results reveal how seriously Warren is taking the attacks from Trump, who has been able to effectively caricature and diminish his national foes via nicknames and conspiracy theories."

Above, the Rev. John Blount holds a service outside of his church, St. Andrew United Methodist, in Panama City, Fla.

Below, Pastor Geoffrey Lentz walks through the sanctuary of his church, First United Methodist in Port Saint Joe, Fla.

As you enter the Carne y Arena experience in Northeast Washington, a bleach bottle that was used as a water bottle for a border crossing is real. So are the rows of abandoned kids' sneakers.

• Inside, the reality is virtual: An elderly lady collapses in the desert. A chopper buzzes you, INS agents roll up and start shouting, a ferocious dog lunges.

Washingtonians have just two more weeks to visit Carne y Arena, which will give you a vivid sense of the human side of the immigration debate — a topic so often reduced to jargon and statistics.

• At 8 a.m. today, tickets become available for the final run of Carne y Arena, through Oct. 31.
• The experience is open every day 9 a.m. until 9 p.m., including weekends.
• The Emerson Collective, which helped produce and finance the exhibition, tells me: "We’ve had over 7,500 guests come through, including Members of Congress, the Administration, ambassadors, curators and staff from nearly every museum in D.C., media, high schoolers, university students, teachers, artists, advocacy organizations, activists and average citizens. Over the summer, we had people fly from all over the country come just to see it."

What you'll see: "Academy Award-winning director Alejandro G. Iñárritu’s conceptual virtual reality installation CARNE y ARENA (Virtually present, Physically invisible) explores the human condition of immigrants and refugees. Based on true accounts from Central American and Mexican refugees, CARNE y ARENA blurs and binds together the superficial lines between subject and bystander, allowing individuals to walk in a vast space and live a fragment of a refugee’s personal journey."

• Each visitor experiences the exhibit individually, but groups are welcome.
• This is beyond worthy of your time. Reserve your space here.

Two parallel efforts to tax carbon emissions are taking great strides to avoid the t-word, Amy Harder writes in "Harder Line," her weekly energy column:

• Why it matters: Because words matter! And "tax" is at the intersection of our fossil-fuel dependence, the climate-change repercussions of that, and what (if anything) is done about it.

What's new:

• Washington state’s November ballot has an initiative to put a price on carbon emissions, and proponents call it a fee. They cite a state law defining the difference between taxes and fees. A similar ballot initiative two years ago was officially called a tax — and that's one of the reasons it failed.
• Backers of a separate push to get a carbon tax passed at the federal level have recently shifted their language to use "fee" instead of "tax." That lobbying effort just received million-dollar backing by ExxonMobil.

Go deeper, with Amy's other glossary columns:

• Climate and energy glossary for Trump (and everyone).
• A power primer for the Trump era.
• What other words should she dissect? Email [email protected].

Jim Rutenberg's N.Y. Times weekly media column, "The Mediator," returns ... "Just six months ago, American media outlets presented a sunny-side-up portrait of Crown Prince Mohammed bin Salman of Saudi Arabia as he made a good-will tour of New York, Hollywood and Silicon Valley."

• With the disappearance, and apparent killing, of Saudi journalist Jamal Khashoggi, "suddenly the 'M.B.S.' moniker took on a grim new meaning among the plugged-in set of Washington: Mister Bone Saw."
• "[T]here’s a streak in American journalism to allow glittering narratives about budding authoritarians to obscure less appealing facts."
• The kicker: The crown prince was named Oct. 3 to Vanity Fair’s annual New Establishment.

A foiled plot to bomb a rally of Iranian dissidents in Paris "has sparked growing anxiety in France, Germany and several other countries, including the United States and Israel, that Iran is planning audacious terrorist attacks and has stepped up its intelligence operations around the world," per the WashPost:

• Iranian leaders are "under pressure from domestic protesters, Israeli intelligence operatives and the Trump administration, which is reimposing economic sanctions lifted under President Barack Obama."

The leaders "are making contingency plans to strike at the country’s adversaries in the event of open conflict, according to American, European, Middle Eastern and Israeli officials and analysts."

• "Iran has assigned ... surveillance of opposition figures, as well as Jewish and Israeli organizations, in the United States and Europe."

This is a smart way to think about last week's stock shock ..."Here’s Why More Scares Are Ahead for the Stock Market, by Ben Levisohn of Barron's:

• "When stocks bounced on Friday, it delayed a true washout, but there are likely to be more scares, more drops, more pain, before stocks start heading higher again. 'The process can look like a shampoo commercial,' says Christopher Harvey, head of equity and quant strategy at Wells Fargo Securities. 'Lather (selloff), rinse (rebalance), and repeat.'"

Meghan Markle, 37, the Duchess of Sussex, is pregnant and due to give birth next spring, per BBC:

• Kensington Palace announced the news as she and Prince Harry, 34, begin a tour of Australia. They were married five months ago.
• "Their baby will be seventh in line to the throne."

"The Queen and other senior royals were told about the pregnancy on Friday, when members of the Royal Family gathered in Windsor for Princess Eugenie's wedding."

• "Meghan attended the wedding with Prince Harry, wearing a long, dark blue coat, which sparked speculation she could be expecting."