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

As a rebuttal to USA Today's editorial imploring people to vote for anyone but Donald Trump, his running mate wrote a screed of his own, calling Trump a "bold leader" not unlike GOP icon Ronald Reagan.

"In a political world often reserved for talkers, Donald Trump is a doer," Pence said. Over time, Pence has found Trump to be "thoughtful, compassionate, and steady," and a lot like Reagan, who also "made some Republicans uneasy" when he entered politics. "Along the way, people heard his vision of a renewed America," Pence continued. "Americans from all walks of life flocked to a man who was so clearly unbound by Washington niceties and political correctness. Ronald Reagan spoke the truth in 1980 to the American people, just as Donald Trump has in 2016."

Hillary Clinton, Pence wrote, will bring "more taxes, more spending, more regulation, and more government," while Trump will cut taxes, repeal Obamacare, and "rewrite our trade deals so they help American workers." The choice is clear, Pence says, and only Trump has the "courage to speak his mind and the boldness to make true his vision of a renewed America." Catherine Garcia

The Donald J. Trump Foundation does not have the certification New York requires for charities to solicit money from the public, the state attorney general's office told The Washington Post.

Under New York law, any charity that solicits more than $25,000 a year from the public must obtain registration beforehand, reports David Fahrenthold, and a charity the size of the Trump Foundation must also submit to an audit that asks if it spent any money to personally benefit its officers. The Trump Foundation was established in 1987 as a way for Trump to give away proceeds from his book, The Art of the Deal, but began taking donations from others in the early 2000s. One example of public solicitation took place earlier this year, when the Trump Foundation asked for donations online to give to veterans, later saying it raised $1.67 million through the site. Tax filings also show that each year during the past decade, the foundation raised more than $25,000 from outsiders, the Post reports. The Trump campaign did not respond to the Post's request for comment.

If New York Attorney General Eric Schneiderman (D), who is already looking into the charity, finds that the Trump Foundation violated the law while raising money, he could order the foundation to immediately stop its fundraising efforts, and with a court's permission, it could be ordered to give back the money it has raised. One expert in charity law told Fahrenthold he was surprised by Trump's rookie move. "He's a billionaire who acts like a thousandaire," said James J. Fishman, a professor at Pace University's law school in White Plains, New York. "You wouldn't expect somebody who's supposed to be sophisticated, and brags about his business prowess, would run his foundation like this." Catherine Garcia

USA Today's editorial board has never before chosen sides in a presidential race, and while they were unable to come up with a consensus for a Hillary Clinton endorsement, they did unanimously agree that Donald Trump is "unfit for the presidency."

Every four years, the editorial board revisits their policy against endorsing a candidate, and every four years, they stick with it. This time around, the board explained, it was different. Trump, the board wrote, "has demonstrated repeatedly that he lacks the temperament, knowledge, steadiness, and honesty that America needs from its presidents." He is "ill-equipped to be commander in chief," with "foreign policy pronouncements" that "typically range from uninformed to incoherent." Further, he is so "erratic" that "attempting to assess his policy positions is like shooting at a moving target," and he "traffics in prejudice," is a "serial liar," and has "coarsened the national dialogue."

The editorial urges voters to "stay true" to their convictions, but "resist the siren song of a dangerous demagogue. By all means vote, just not for Donald Trump." Read the entire damning editorial at USA Today. Catherine Garcia

There's been a drop in the number of people getting the flu vaccination, a trend that's worrying infectious disease specialists.

"Flu is serious. Flu is unpredictable," Dr. Thomas Frieden, director of the Centers for Disease Control and Prevention, told reporters Thursday. "Flu often does not get enough respect." In 2015, about 45 percent of the U.S. population received vaccinations, down 1.5 percentage points from 2014, the CDC reports. The largest decrease was in people 50 and up — there was a 3.4 percent drop among people between the ages of 50 and 64, and a 3.3 percent decline among people 65 and over. While most people are hit with mild symptoms, the flu kills 100 children every year, and the elderly are among the most vulnerable to the virus.

While the CDC is urging Americans to get a flu shot now, they are not recommending the nasal spray vaccine, which is often used on kids, due to questions surrounding the vaccine's effectiveness. This year, there are also two new vaccines, NPR reports; one protects against four strains of the flu rather than three, and the other has an "adjuvant," which increases its effectiveness. The CDC expects as many as 168 million vaccines will be available, so "there's plenty for everybody," Frieden said. Catherine Garcia

The New Jersey medical examiner has identified the victim in Thursday morning's train crash in Hoboken as Fabiola Bittar de Kroon, 34.

De Kroon was a resident of Hoboken and native of Brazil, who once worked as a lawyer there at the computer software company SAP, NBC New York reports. She recently moved to Hoboken with her family, and her young daughter was in day care at the time of the accident, which left at least 114 people injured. Officials said de Kroon was waiting on a platform when the New Jersey Transit train came careening into the terminal, and she was hit by falling debris. Catherine Garcia

Hillary Clinton says a Newsweek story about Donald Trump allegedly violating the U.S. trade embargo against Cuba shows he's "puts his personal and business interests ahead of the laws and values and policies of the United States of America."

While investigating the story, published Thursday, Newsweek interviewed former executives of Trump Hotels & Casino Resorts and looked at court filings and company records. They found that in 1998, Trump wanted to get into the Cuban market, and sent a consulting firm to Havana on its behalf to find any business opportunities. The company allegedly spent at least $68,000 in Cuba, without U.S. permission, and Newsweek says they made it appear as though the trip was connected to a Catholic charity. In 1999, Trump wrote in a Miami Herald column that he refused to do business in Cuba because "it would place me directly at odds with the longstanding U.S. policy of isolating Fidel Castro. I had a choice to make: huge profits or human rights. For me, it was a no-brainer."

Trump's campaign manager, Kellyanne Conway, said on Thursday the money was never paid, giving the only statement so far from the Trump camp, the BBC reports. The Cuban-American vote in Florida is huge, and Sen. Marco Rubio (R-Fla.), who has endorsed Trump, told an ESPN/ABC podcast he hopes "the Trump campaign is going to come forward and answer some questions about this, because if what the article says is true — and I'm not saying that it is, we don't know with 100 percent certainty — I'd be deeply concerned about it." Catherine Garcia

A New Jersey Transit commuter train crashed Thursday morning at a station in Hoboken, New Jersey. At least 114 people were injured, New Jersey Gov. Chris Christie (R) told CNN on Thursday afternoon, with many in critical condition. At least one person is confirmed dead.

"I got off my train on the way into work and as I was walking through the station, we could see that a train had come through the place where it's supposed to stop, all the way into the station — not into the waiting room but into the outdoor part," said Nancy Solomon of New York radio station WNYC. Photographs of the crash show significant damage to the station, including a partial collapse of the roof.

The crash happened at the height of the morning commute, around 8:45 a.m., though the number and severity of injuries is still unclear. Preliminary investigation suggests the incident was either accidental or caused by operator error. Full service is expected to resume for evening rush hour.

This post has been updated throughout. Jeva Lange