Add former South Carolina Gov. Mark Sanford (R) to the list.

Sanford announced Sunday that he will challenge President Trump in the Republican primaries, joining former Rep. Joe Walsh (R-Ill.) and former Massachusetts Gov. Bill Weld (R) in doing so. "I'm here to tell you now that I am going to get in," he told Chris Wallace on Fox News Sunday. "As a Republican Party, we have lost our way."

Sanford was long-rumored to launch a presidential campaign, which is likely to remain a long shot. Sanford will seemingly emphasize the increasing national debt and the need to cut back on deficit spending, though he also said he believes the country needs "to have a conversation about humility," indicating there will be a cultural aspect to the campaign, as well.

Sanford is not without his own past controversies, however — in 2009, while serving as governor, he disappeared for nearly a week, eventually admitting he was in Argentina having an extramarital affair. When asked about it by Wallace, Sanford explained he "profoundly apologized for that," which he said sets him apart from Trump. Read more at The Hill and Fox News. Tim O'Donnell

President Trump just signed a series of coronavirus pandemic-related executive orders in an attempt to bypass a congressional stalemate over an economic relief bill. Naturally, the people who were at the negotiating table the last few weeks had some thoughts.

House Speaker Nancy Pelosi (D-Calif.) and Senate Minority Leader Chuck Schumer (D-N.Y.) on Sunday echoed critics who have called the president's orders unconstitutional and weak. Pelosi told Fox News' Chris Wallace the orders are "illusions," with Schumer adding during an appearance on ABC's This Week that they don't "do the job."

Meanwhile, Treasury Secretary Steven Mnuchin, who sat on the other side of the table, defended the actions, arguing that Pelosi and Schumer had a chance to accept the White House's offer of continuing to pay $600/week enhanced unemployment benefits — which would be reduced to $400/week under Trump's order — during negotiations, but "turned that down." Mnuchin said Democratic lawmakers will have "a lot of explaining to do" if they challenge the executive actions in court, which seems likely at this point. Read more at The Hill. Tim O'Donnell

Face the Nation host Margaret Brennan repeatedly pushed National Security Adviser Robert O'Brien on Sunday to say whether President Trump has told Russian President Vladimir Putin "to knock it off" when it comes to U.S. election interference. O'Brien said he doesn't get involved with his boss' conversations with other world leaders, but said the Trump administration remains committed to keeping Moscow out of the picture.

Trump, O'Brien said, has been tougher than his predecessors. So much so, he argues, that there's little else Washington can do since they've already "sanctioned the heck out of" individuals, companies, and the government in Russia, kicked Russian spies out of the U.S., and closed down consulates and other diplomatic facilities. "Nevertheless we continue to message the Russians, and President Trump continues to message the Russians: don't get involved our elections," O'Brien said, adding that the warning extends to Beijing and Tehran, as well.

Brennan, however, pointed out throughout the interview that intelligence reports indicate that the messaging — and the sanctions — don't seem to have gotten through to the Kremlin, as there's still evidence Russia is working to undermine the electoral process stateside. Foreign policy experts have also suggested current sanction policy doesn't always prove to be a deterrent, since Moscow views them as permanent and therefore has little incentive to change its behavior purely based on those actions. Tim O'Donnell

The coronavirus is a serious, often-deadly pathogen, yet the Centers for Disease Control and Prevention estimates 40 percent of all cases are asymptomatic. In some isolated outbreaks in prisons and food processing plants where thousands of people contracted COVID-19, as many as 94 percent of infected individuals presented no symptoms. The Washington Post spoke to experts and suggested four possible reasons as to why, though it's important to note the research in all cases is in early stages.

T-Cells: T-cells, a type of white blood cell that generally provides longer-lasting immunity than antibodies, may be the key to understanding resistance. One research group found that, among uninfected blood samples donated to a blood bank between 2015 and 2018, a "remarkable" 40 to 60 percent recognized the coronavirus, suggesting some people may have an immune response based on memory of other, less potent coronaviruses.

Vaccines: The Mayo Clinic is studying whether vaccines for other pathogens can protect against the virus, as has been proven in other situations. Seven types of vaccines given one, two, or five years in the past were found to be associated with a lower rate of coronavirus infection, particularly pneumonia and polio vaccines.

Allergies: Scientists have noted children with asthma and allergies surprisingly don't seem to be at high risk of developing serious cases of COVID-19. One theory is that those children have a reduced number of ACE2 receptors, the protein the virus latches onto before replicating inside the body. Without those receptors, the virus' chance of causing damage could decrease, meaning allergies may offer protection in this case.

Masks: Masks are discussed as a preventative measure, but they may contribute to more mild infections, as well. The most direct evidence of this theory is a comparison of two cruise ships. On the Diamond Princess, where masks weren't used, 47 percent of the positive cases were asymptomatic, whereas an Antarctic-bound Argentine cruise ship that had a similar outbreak, but provided masks to all passengers and crew, saw an 81 percent asymptomatic rate. Read more at The Washington Post. Tim O'Donnell

One of the coronavirus pandemic-related executive orders signed by President Trump addressed evictions, but critics say it's a weak move that doesn't actually extend a moratorium. Instead, the order merely directs the Treasury Department and the Department of Housing and Urban Development to consider taking action, Josh Blackman writes for Reason.

In short, the order instructs the two departments to look into identifying federal funds that could potentially provide assistance to renters and homeowners who can't meet their monthly rental and mortgage payments because of the pandemic. There are no guarantees.

Similarly, observers believe the payroll tax deferral order was overplayed, since taxpayers will still ultimately owe the money next year.

Trump has said he'd try to terminate the tax altogether if he's re-elected, but it's unclear if he has the authority do so, and he would likely face bipartisan opposition in Congress. Tim O'Donnell

It's not hard to read between the lines of Health and Human Services Secretary Alex Azar's visit to Taiwan to meet with health officials about the coronavirus pandemic.

Azar arrived Sunday, making him the highest-ranking U.S. cabinet official to embark on a diplomatic visit to the island since 1979 when Washington broke relations with Taipei as a concession to China, which claims Taiwan as a territory. Since then, the U.S. has remained a de facto ally of Taiwan, but has largely refrained from demonstrating any semblance of official ties. The Trump administration has increasingly played fast and loose with those guidelines of late, however, as the U.S.' relationship with China deteriorates, especially in light of the pandemic. And it certainly feels like Azar's trip is part of the possible "strategic shift," The Financial Times reports.

While some experts acknowledge Taiwan deserves better treatment from the U.S., there's also a sense that Washington is creating risks for Taipei, FT reports. "We ought to push the envelope because the envelope was sealed by us, and we have opened it before," said William Stanton, a former director of the American Institute in Taiwan. "But there is the worry — and it is one Taiwan needs to consider as well — that the China threat is constantly there."

Additionally, Shelley Rigger, a professor at Davidson College and a leading Taiwan expert, told FT she isn't sure how serious President Trump is about supporting Taiwan and predicted he could back down if things with China really get heated, leaving the island vulnerable. "If I were Beijing, I would be asking myself: 'If the U.S. gives us a justification to attack Taiwan, what are the odds that he will change is pattern of cutting and running?" Rigger said. Read more at The Financial Times. Tim O'Donnell

An Afghan grand assembly of elders, known as the Loya Jirga, on Sunday passed a resolution to release 400 Taliban prisoners, and President Ashraf Ghani said he will sign the order, effectively removing one of the most important barriers to peace talks between the government and the Taliban, who have been in conflict for decades.

The United States and the Taliban had previously agreed the latter would enter talks with the Afghan government if it released 5,000 prisoners, most of whom have already been freed. But Kabul was hesitant to release the final 400, many of whom are accused of serious offenses, with more than 150 of them on death row. The Loya Jirga said they wanted guarantees the Taliban would not return to the battlefield during negotiations, and Ghani said "the choice is in the Taliban's hands ... the Taliban should show today they don't fear a nationwide cease-fire."

Some civilians and human rights group are wary of the move, but negotiations between the factions are expected to begin next week in Qatar. Read more at Al Jazeera and BBC. Tim O'Donnell