Former Rep. Joe Walsh (R-Ill.), now a conservative talk radio host, announced Sunday that he's challenging President Trump for the 2020 Republican nomination. People are skeptical of his motives but mostly his chances — New York Magazine called it a "beyond-long-shot primary bid," a "quixotic mission" undertaken with "Bill Kristol, a onetime mighty Republican figure who has become an avatar of GOP Establishment impotence in the face of Trump's party takeover." Another prominent #NeverTrump conservative, George Conway, is also on board, figuratively if not officially.

Trump's campaign doesn't seem very concerned about Walsh's bid. "Whatever," communications director Tim Murtaugh told ABC News.

Walsh told ABC News his campaign's big gamble "is that there are a lot of Republicans who feel like I do," that Trump is "nuts, he's erratic, he's cruel, he stokes bigotry, he's incompetent," and "he's a child," and they're also "sick of this guy's tantrum." He added that he thinks his campaign "will catch on like wildfire." "And if you're wrong?" host George Stephanopoulos asked. "If I'm wrong, it was the right fight, because somebody had to do this."

Journalist Kurt Eichenwald put it this way:

It's true that Walsh "possesses the conservative bona fides" and grit Trump's other GOP challenger, former Gov. William Weld (Mass.), lacks, and "some previous primary candidates have found some success against weak incumbents; think Ronald Reagan in 1976 or Pat Buchanan in 1992," New York adds. "The problem for Walsh — or any other conservative challenger — is that Trump remains extremely popular with GOP voters." Walsh bets the polls are wrong — an idea Trump supporters, at least, can respect. Peter Weber

Pete Buttigieg on Tuesday released the names of nine clients he worked with during his time at McKinsey and Co., a management consulting firm.

Buttigieg, the mayor of South Bend, Indiana, and a 2020 Democratic presidential candidate, worked with Blue Cross Blue Shield of Michigan; the Canadian supermarket chain Loblaws; Best Buy; the Environmental Protection Agency; the Natural Resources Defense Council; the U.S. Department of Defense; the U.S. Postal Service; the Department of Energy; and the environmental nonprofit Energy Foundation. Buttigieg was employed by McKinsey from 2007 to 2010.

The names were revealed after McKinsey released Buttigieg from a nondisclosure agreement on Monday, following pressure from fellow 2020 candidate Sen. Elizabeth Warren (D-Mass.), who said voters should know about any conflicts of interest he might have. In turn, Buttigieg called on Warren to share details about her corporate legal work; she released her records on Sunday night.

In addition to sharing the names, Buttigieg also explained the work he did for each client. "Now, voters can see for themselves that my work amounted to mostly research and analysis," he said in a statement. "They can also see that I value both transparency and keeping my word. Neither of these qualities are something we see coming out of Washington, especially from this White House." Catherine Garcia

The Navy has suspended flight training for Saudi military students at three bases in Florida, following last week's shooting at Naval Air Station Pensacola by a member of the Saudi Royal Air Force.

About 300 Saudi students will be affected, the Navy said Tuesday. While flight training is suspended, classroom instruction will continue. Three people were killed and eight injured in Friday's attack, and the gunman, Mohammed Saeed Alshamrani, 21, was shot and killed by a sheriff's deputy. His motive remains unknown, and the FBI is operating on the assumption the shooting was an act of terrorism.

The FBI on Tuesday said Alshamrani obtained a state hunting license on July 11 and then legally purchased a Glock 45 9 mm handgun on July 20. Under federal law, people who come to the United States on nonimmigrant visas are banned from having a weapon or ammunition, The New York Times reports, but there are exceptions — including for those who have a valid hunting license. This "loophole" should be closed, Florida Gov. Ron DeSantis (R) said on Sunday, adding, "I'm a big supporter of the Second Amendment, but the Second Amendment applies so that we the American people can keep and bear arms. But it does not apply to Saudi Arabians." Catherine Garcia

Lucky number seven?

Businessman Andrew Yang will return to the Democratic presidential debate stage next week in Los Angeles after he picked up 4 percent in the latest national qualifying poll from Quinnipiac University on Tuesday, just two days before the cut-off.

He'll join six other candidates who have already qualified, including former Vice President Joe Biden, South Bend, Indiana, Mayor Pete Buttigieg, billionaire Tom Steyer, and Sens. Amy Klobuchar (D-Minn.), Bernie Sanders (I-Vt.), and Elizabeth Warren (D-Mass.). It's the field's final chance to duke it out in a debate before the primary gets rolling with early voting states like Iowa and New Hampshire in February.

Yang was able to secure a spot despite stricter polling standards that have left most of his competitors out in the cold. Sen. Cory Booker (D-N.J.) and Rep. Tulsi Gabbard (D-Hawaii) — who said she won't attend the debate even if she qualifies — for example, have apparently crossed the fundraising threshold, but don't have the polling numbers. Tim O'Donnell

The FBI issued a warning about a hunting license loophole months before it was used to obtain a gun by Mohammed Alshamrani, who killed three people at Naval Air Station Pensacola in Pensacola, Florida, last week, Yahoo News reports.

Per Yahoo, the agency sent around a report in May that warned business about the possibility of "extremists and other criminal actors" exploiting a federal exception allowing "non-immigrant visa holders" to legally purchase firearms via a hunting license or permit. The alert noted that terrorist organizations like the Islamic State "have encouraged" people to find workarounds in U.S. gun-purchasing laws "to conduct mass casualty shooting attacks in their home countries."

The FBI confirmed Tuesday that Alshamrani obtained his weapon through the hunting license exemption, but the retailer he reportedly bought it from declined to say whether the store received the FBI's warning. While the 21-year-old member of the Royal Saudi Air Force, who was an aviation student at the base, does not appear to have any direct links to international organizations like ISIS, the shooting is being investigated as a terrorism incident.

Florida Gov. Ron DeSantis (R) is now reportedly "at a minimum" advocating for "improved vetting" of foreign nationals seeking to purchase firearms, though he remains a "strong proponent of the Second Amendment for United States citizens," a spokeswoman, Helen Aguirre Ferré said. Read more at Yahoo News. Tim O'Donnell

Yes, the USMCA is facing further delays. No, Democrats aren't the chief cause.

After House Democrats announced Tuesday they'd crafted a on a U.S.-Mexico-Canada agreement they and the White House could both agree on, House Republicans started pushing for an immediate vote on the trade deal. But it was Senate Majority Leader Mitch McConnell who's stopping their wishes, saying Tuesday the Senate wouldn't see the trade deal until at least next year.

Republicans followed Democrats' Tuesday USMCA press conference with one of their own, with the top Republican on the Ways and Means committee Rep. Kevin Brady (Texas) calling out "much delay by Democrats" before the trade deal got here. Then the calls for scratching out further stalling began pouring in. Brady tweeted that Congress "must pass USMCA without delay," as did Rep. George Holding (R-N.C.) and House Minority Whip Steve Scalise (R-La.).

But it seems McConnell wasn't listening. Even though Senate Majority Whip John Thune (R-S.D.) said the Senate will only have 30 days to vote on the USMCA once the House passes it, McConnell said the body wouldn't consider the USMCA before its holiday recess. That leaves it for next year and, considering the Senate has already wiped out its January calendar as it buckles down for an impeachment trial, pushes the USMCA to a rule-breaking February arrival date. Kathryn Krawczyk

Warming air and water temperatures, eroding sea ice, and wildlife showing signs of stress — the Arctic Report Card for 2019 portrays a rapidly changing climate and ecosystem.

The National Oceanic and Atmospheric Administrations' report, released Tuesday, outlines how arctic ecosystems and communities are at risk. Meanwhile, world leaders are at the COP25 climate summit in Madrid working on ways to approach the crisis.

Scientists noted that feared climate change acceleration may already be underway. The soil underneath Arctic permafrost contains about twice as much carbon as is currently in the atmosphere, per the report. As temperatures rise, this carbon is released into the atmosphere in the form of greenhouse gasses, creating a loop of climate change acceleration.

"We've turned this corner for Arctic carbon," Ted Schurr, a researcher at Northern Arizona University who was involved with the report card, told The Washington Post, and the amount of carbon emitted in the Arctic will continue to grow. This will make achieving carbon-cutting goals of the Paris Climate Agreement even more difficult.

Indigenous Elders in the Bering Sea region are among the first groups of people to experience hardships of climate change, as the Arctic region is warming twice as fast as the global average. The report states that climate change is threatening their "homes, schools, airports, and utilities."

"We fear for our young people," they said in the report. "We worry that they will grow without the same foods and places that we have known throughout our lives."

The Arctic report card was the 14th annual from the NOAA, and was developed by 81 scientists from 12 countries. Taylor Watson