President Trump's first possible challenger in the Republican presidential primaries has emerged.

Former Massachusetts Governor Bill Weld announced on Friday that he's forming an exploratory committee ahead of a possible run against Trump in 2020, reports the Boston Herald.

In his announcement, Weld said that the country is in "grave peril" and that Trump is "unstable." He also said that Republicans who support the president "exhibit all the symptoms of Stockholm Syndrome."

Weld was Libertarian candidate Gary Johnson's running mate during the 2016 election, but he was a registered Republican prior to running with Johnson, and he changed his registration back from Libertarian to Republican this month ahead of this potential White House bid.

Several Republicans have floated possible primary challenges against Trump, including former Ohio Governor John Kasich, but Weld is the first one to actually reach the exploratory committee step. His 2020 campaign is certainly a long-shot effort, especially with polls showing that the vast majority of Republicans still back the president. But even so, the Boston Herald writes that Weld is "determined to make life difficult for Trump." Brendan Morrow

The Trump campaign suffered another legal defeat Friday when the Third Circuit Court of Appeals denied an attempt to challenge a lower court loss.

The original lawsuit, based on unfounded claims of voter fraud, sought to stop or reverse the certification of Pennsylvania's vote; Gov. Tom Wolf (D) signed off on the results earlier this week, sending the Keystone State's 20 electoral votes to President-elect Joe Biden. Judge Stephanos Bibas, who was appointed by President Trump, wrote on behalf of the appellate court, stating that "charges of unfairness are serious. But calling an election unfair does not make it so. Charges require specific allegations and then proof. We have neither here."

After the ruling, Jenna Ellis, one of Trump's lawyers, said she and Rudy Giuliani would appeal to the Supreme Court, calling the three judges on the panel — all of whom were nominated by Republican presidents — "the activist judicial machinery in Pennsylvania" and accusing them of covering up "allegations of massive fraud." Read more at The New York Times and The Associated Press. Tim O'Donnell

The S&P 500 and the Nasdaq Composite closed at record highs when Wall Street shuttered early Friday at the end of the holiday week, adding 0.2 percent and 0.9 percent, respectively. Both indexes had previously set high marks earlier in the week.

The Dow Jones Industrial Average also shot up, but fell short of reaching the milestone it set earlier this week when it surpassed 30,000 for the first time ever. All three major benchmarks capped off huge weeks, trading up 2 percent since the opening bell Monday. Indeed, global stocks were on pace to cap off their most successful month on record Friday, The Financial Times notes.

The gains are likely tied somewhat to optimism about President-elect Joe Biden's victory, but the major driver is the encouraging coronavirus vaccine news that has steadliy rolled out in recent weeks. That has investors banking on a resurgent economy next year. "It's incredible, absolutely stunning," Fahad Kamal, chief market strategist at Kleinwort Hambros, said of the upswing, noting it's "all linked back to one crucial factor and that's the vaccine." Read more at The Wall Street Journal and The Financial Times. Tim O'Donnell

Mohsen Fakhrizadeh, a nuclear scientist suspected of leading Iran's nuclear weapons program, was shot and killed Friday while traveling in a vehicle east of Tehran, Iranian state media said. He was apparently taken to the hospital for treatment, but doctors were unable to save him.

Fakhrizadeh has long been a top target of the Israeli intelligence service Mossad, and Israeli Prime Minister Benjamin Netanyahu publicly singled him out in 2018. Iranian Foreign Minister Javad Zarif believes Jerusalem was behind the assassination, but a spokesperson for the Israeli military refused to comment. Hossein Dehghan, a military commander and adviser to Iran's supreme leader, Ayatollah Ali Khamenei, vowed retaliation against whomever the perpetrators are. "We will strike as thunder at the killers of this oppressed martyr and will make them regret their action," he tweeted.

Not much is known about Fakrizadeh, believed to be 59, but a 2007 CIA assessment said his role as a physics professor was likely a cover story, and it later became clear he was in charge of Iran's warhead development, The New York Times reports. Iran has denied ever seeking a nuclear weapon, but an Israeli mission in 2018 uncovered documents detailing such a project that was in place 20 years ago. Even after that was seemingly abandoned, Israeli and American intelligence officials say, it appears Fakhrizadeh was covertly overseeing the program.

The alleged assassination will likely add another roadblock for the incoming Biden administration, which already faced an uphill climb in its hopes of at least partially re-establishing some sort of nuclear pact with Iran, the Times notes. Read more at The Guardian and The New York Times. Tim O'Donnell

There's a reason why North Korea has remained quiet about the United States presidential election, The Associated Press reports.

South Korean lawmakers were briefed by the country's National Intelligence Service on Friday, and one of the issues reportedly addressed was Pyongyang's anxiety about the incoming Biden administration. The briefing's contents could not be independently verified by news organizations, but Seoul's spy agency alleges North Korea has ordered overseas diplomatic missions to refrain from provoking the U.S., reportedly warning its ambassadors there will be consequences should any of their acts or comments rattle folks in Washington.

One South Korean lawmaker said the NIS believes North Korea is nervous that the friendly relationship between President Trump and North Korean leader Kim Jong Un will be rendered moot when President-elect Joe Biden steps into the Oval Office in January, so the government apparently wants to ensure tensions remain relatively at ease for now. The NIS does expect North Korea will hold a military parade around the same time as Biden's inauguration as a show of force, although they've done so with Trump in office, as well. Read more at The Associated Press. Tim O'Donnell

Thomas Cueni, the director-general of the International Federation of Pharmaceutical Manufacturers and Associations, said Friday that as many as 10 COVID-19 vaccines could be available by the middle of next year, as long as they are granted approval by regulatory agencies.

Cueni noted that the vaccine developers that have already released info from late-stage trials — Pfizer and BioNTech, Moderna, and the University of Oxford and AstraZeneca — have all showed promising results. Moderna and Pfizer both reported higher than 90 percent efficacy rates, while the Oxford-AstraZeneca trial has sparked some confusion after the accidental discovery that a lower dosing regimen proved more effective than the full one. The trial is being amended, but even the study's lower 62 percent efficacy rate for the full dosing regimen would meet the United States' 50 percent threshold, and the European Union is not setting a minimum efficacy level, so if it passes the regulatory observation the U.K. government is moving forward with, it will likely be gearing up for global deployment.

Beyond that trio, Cueni suggested Johnson & Johnson, Novavax, Sanofi Pasteur, GSK, and Merck have a good chance of following suit in the coming months. "But all of them need to be submitted by rigorous scientific scrutiny by the regulators," he said. Read more at Reuters. Tim O'Donnell

President Trump said Thursday he will "certainly" leave the White House if the Electoral College, as expected, casts its votes for President-elect Joe Biden on Dec. 14, formalizing his victory.

Taking questions from reporters for the first time since the election after addressing U.S. troops stationed around the world on Thanksgiving, Trump was asked if he would depart on his own accord. "Certainly I will, and you know that," he said. The Washington Post notes it was the first explicit commitment Trump has made about vacating the White House, although his advisers have maintained he would do so for some time.

That said, Trump remains determined to expose the widespread voter fraud he claims occurred in swing states, despite there being no evidence there was any. "It's going to be a very hard thing to concede, because we know that there was massive fraud," he said.

Trump also said he's decided whether he will attend Biden's inauguration, but he wanted to keep the suspense going and refused to reveal the answer. "I don't want to say that yet," he said. Read more at The New York Times and The Washington Post. Tim O'Donnell