Donald Trump is widely expected to win Nevada's Republican caucus on Tuesday, even though he's a little fuzzy on the rules. "What the hell is caucus?" he asked an estimated 8,000 supporters at a rally in Las Vegas on Monday night. "Nobody even knows what it means." And nobody really has any idea who will turn up to vote, thanks to sparse polling, Nevada's unpredictable electorate, and questions over where Jeb Bush's voters will land. Marco Rubio, who lived in Nevada for a spell as a child — when his family briefly converted to Mormonism — has been working to court the organized Mormon and moderate Republican votes, while Ted Cruz has been heavily courting evangelical Christians and people opposed to federal ownership of public lands.

And it wouldn't take many of those voters to push Rubio or Cruz to an upset victory over Trump, says Philip Rucker at The Washington Post. "Just 20,000 voters could be enough for a landslide, operatives here say," meaning that for either candidate, "a win is within reach." Nevada has 434,000 registered Republican voters. So as Nevada Lt. Gov. Mark Hutchison, Rubio's state campaign chairman, said at a Rubio rally Sunday night: "If we get our people out, we’re going to do great. If we don’t get our people out, we're not going to do so great." Peter Weber

Police overseeing the investigation into Monday night's suicide bombing at an Ariana Grande concert in Manchester have stopped sharing information with American counterparts, BBC News reports, after U.S. officials allegedly leaked information about the attacker and his explosive to the press before British police wanted the information released. The Greater Manchester Police are "furious" at the leaks, BBC News says, and there is "disbelief and astonishment" across the British government at photos of the exploded bomb published in The New York Times.

Home Secretary Amber Rudd said she is "irritated" by the U.S. leaks, Manchester Mayor Andy Burnham said late Wednesday the information leaking "troubles him" and he's "made known my concerns about it to the U.S. ambassador," and in a statement on Wednesday, Britain's National Police Chiefs' Council said such "unauthorized" disclosures undermined this "major counter-terrorism investigation" and breached bonds of trust. Prime Minister Theresa May said, when she arrives in Brussels Thursday, "I will make clear to President Trump that intelligence shared between our security agencies must remain secure."

Britain has arrested nine people in connection with the attack, with eight still in custody, and Libyan authorities detained attacker Salman Abedi's father and younger brother. Manchester Chief Constable Ian Hopkins said Wednesday that "it's very clear that this is a network that we are investigating."

"The police decision to stop sharing information specifically about the Manchester attack with their security counterparts in the U.S. is a hugely significant move and shows how angry British authorities are," says BBC home affairs correspondent Dominic Casciani. "The information from the crime scene wasn't shared on a whim: the British and Americans have a lot of shared world-leading expertise in improvised explosive devices and scientists would be discussing whether the Manchester device tells them something new that could, ultimately, track down a bombmaker." Other British officials said Americans also leaked key information too early after the last major terrorist attack in Britain, back in July 2005. Peter Weber

If you've been following President Trump's obsession with his election win, and his seeming inability to make small talk about much else, it should come as absolutely no surprise at all that he is boasting about it to world leaders abroad, too.

Trump reportedly "brought up [the] size of his election victory" at the European Union headquarters with European Council president Donald Tusk and European Commission head Jean-Claude Juncker on Thursday morning, an EU official said.

Ahead of Trump's trip, world leaders were reportedly advised to "praise" Trump's Electoral College win. Trump had compliments for more than just himself, though: Upon meeting French President Emmanuel Macron, Trump admired the new president's "incredible campaign" and "tremendous victory." Jeva Lange

Montana goes to the polls Thursday to vote in a special election for the House seat vacated by Interior Secretary Ryan Zinke. On the ballot is Democrat Rob Quist, a folk singer, and Republican multimillionaire Greg Gianforte, who has consistently led the polls despite Quist's recent gains.

The race, described by Gianforte as "closer than it should be," is an uncomfortable repeat for Republicans of close, but ultimately Republican-won, special elections in Kansas and Georgia. Elections like Montana's could indicate how a deeply unpopular president in the White House could influence Republican victories nationwide in 2018.

Complicating matters, Gianforte was charged with misdemeanor assault for attacking a reporter on Wednesday; 37 percent of registered voters have already voted absentee, the Billings Gazette reports. Read more about Quist's chance to win the deep-red state here at The Week. Jeva Lange

On Thursday in Brussels, President Trump will meet for the first time with leaders of the European Union and NATO, the 27-member alliance he once dismissed as "obsolete." Trump arrived in Brussels on Wednesday, after a stop in Italy, and after meeting at the European Union headquarters with European Council president Donald Tusk and European Commission head Jean-Claude Juncker on Thursday morning, Trump will have a private lunch with new French President Francois Macron then gather with fellow NATO leaders.

Trump says he wants to get a NATO commitment to join the fight against the Islamic State, and NATO will almost certainly agree, though some members won't commit military support to the ISIS fight. Trump will also likely ask NATO members to commit to higher military spending, while other nations will be looking for a firm commitment from Trump to support NATO's Article 5 collective-defense pledge. Some 9,000 protesters greeted Trump when he landed in Brussels, and more protests are planned for Thursday, though tight security means the president won't have to confront them. Late Thursday, Trump departs for Sicily and a G7 summit, the final leg of his overseas trip. You can watch Trump arrive at EU headquarters below. Peter Weber

Greg Gianforte, the Republican candidate for Montana's at-large House seat, was charged with misdemeanor assault on Wednesday night after he body-slammed a reporter, Ben Jacobs of The Guardian, for asking him questions about the GOP health-care bill, according to accounts by Jacobs and three witnesses from Fox News. Late Wednesday and early Thursday, three Montana newspapers — the Missoulian, the Helena Independent Record, and the Billings Gazette — rescinded their endorsements of Gianforte, in no uncertain terms. The election is Thursday.

Gianforte "not only lost the endorsement of this newspaper Wednesday night," the Missoulian editorial board wrote, "he should lose the confidence of all Montanans."

We will leave it to the legal system to determine his guilt or innocence. But there is no doubt that Gianforte committed an act of terrible judgment that, if it doesn't land him in jail, also shouldn't land him in the U.S. House of Representatives. ... He does not represent Montana values and he should not represent us in Congress. [Missoulian]

The Independent Review noted that "democracy cannot exist without a free press," saying "both concepts are under attack" by Gianforte, with Wednesday night just being the most serious and latest example. "We cannot in good faith continue to support this candidate," the editorial board said.

The Billings Gazette said called Gianforte's reported actions "shocking, disturbing, and without precedent," and worthy of "rescinding our editorial endorsement." They called him untrustworthy and lacking sound judgment. "We believe that you cannot love America, love the Constitution, talk about the importance of a free press, and then pummel a reporter," the editorial board said, but to make this about press freedoms "would be to miss the point":

If what was heard on tape and described by eye-witnesses is accurate, the incident in Bozeman is nothing short of assault. We wouldn't condone it if it happened on the street. We wouldn't condone it if it happened in a home or even a late-night bar fight. And we couldn't accept it from a man who is running to become Montana's lone congressional representative. We will not stand by that kind of violence, period. [Billings Gazette]

None of the newspapers explicitly endorsed Gianforte's rival, Democrat Rob Quist, but they made it pretty clear who they did not want to see in Congress. You can read the full editorials at the Missoulian, Billings Gazette, and Independent Record, or hear the details in this Associated Press report. Peter Weber

This week, a Philippine transcript of an April phone call President Trump placed to Philippine President Rodrigo Duterte leaked to the press. The Trump administration had already shared that Trump invited Duterte to the White House (he was noncommittal). Regardless, "that's a very exclusive invitation," Stephen Colbert said on Wednesday's Late Show. "Usually you want to save that kind of honor for a true statesman like Ted Nugget." But thanks to the leaked transcript, we also know he started off his call by congratulating Duterte on his "war on drugs" — which, not unlike a real war, has killed 7,000 people over the past year.

"Trump congratulated Duterte on his vigilante kill squads," Colbert marveled. "That's like saying: 'Darth, I'm in construction, and I know that's a fantastic Death Star, top notch. I'd love to have you over sometime to Force-choke Sean Spicer." Still, "the call had an even bigger bombshell," he said. "In a conversation about North Korea, Trump gave Duterte military secrets" about two U.S. nuclear submarines off North Korea. "Come on! That's a state secret," Colbert protested. "Trump has got to be the world's worst Battleship player. 'Okay, you'll never guess where my beautiful submarine is — unless you guess B2, because that's where I put it, 2 through 5.'"

Then Colbert saw an opportunity in Trump's secrets-spilling: "Since the only way we seem to get any information out of Donald Trump these days is via leaked conversations with dictators, I have a favor to ask of Robert Mugabe: Can you call up our president and ask him for his tax returns?" Peter Weber

President Trump is still overseas, Stephen Colbert noted on Wednesday's Late Show. "And he might want to stay over there for a little while, until the firemen can put out his budget proposal. Not only does nobody like it, but it turns out it has a huge mistake in it — not the part about cutting funding for cancer research, that's just one of his passion projects." No, he was talking about the $2 trillion accounting error. "There's a simple explanation for how this happened: Donald Trump is an idiot," Colbert said. "Or he's lying." The fault actually lies with White House budget director Mick Mulvaney, who says the $2 trillion error isn't a mistake, but what fun is that? "Let me see if I can help — here is a basic math lesson for Donald Trump," Colbert said: "If a train leaves Washington, D.C., traveling at 40 mph, please get on it."

Colbert then turned to Trump's visit to the Vatican. "That's exciting — it's one of the few places on Earth with more old white men than his Cabinet," he said. Trump and Pope Francis butted heads over immigration during the presidential campaign, so some people were expecting a tense meeting — and judging from the pope's demeanor, it may have been, he added. But Trump seemed pleased, kind of, saying afterward that the pope "is something." "The pope is, indeed, something," Colbert said. "As Jesus himself said, 'Blessed are the vague, for they shall inherit, you know, stuff.'"

As is traditional, Francis and Trump exchanged gifts, "but the best part of the visit happened at the end," Colbert said, "when the pope threw a little shade at Trump's physique," asking first lady Melania Trump, "What do you give him to eat, potizza?" — a high-calorie pastry from her native Slovenia. "The pope just called the president chubby," Colbert said. "I cannot believe that the infallible vicar of Christ just played the dozens on our president." He turned to Cartoon Pope Francis for some answers, and, well, Cartoon Pope Francis just isn't sorry. Peter Weber