At the end of the month, there will be a referendum to decide if Britain should leave or remain in the European Union. The implications are radical for the United States: Following World War II, the EU brought stability and order to Europe, and as a single unit it has helped the U.S. with geopolitical responsibilities around the world. On the economic front alone, President Obama has urged against a Brexit, saying it could take as many as 10 years for Britain to negotiate new trade deals with the U.S.

"Brexit is not the source of Europe's trend of disintegration," Vox explains, "But if it happens, it could be the beginning of the end for the most successful U.S. foreign policy ever and a serious blow to U.S. efforts to maintain stability and order in Europe and therefore beyond."

In other words, it is a really big deal.

Enter Donald Trump:

"If there's any pattern to [Trump's] conversation, it's that he's vague on all subjects outside himself, his campaign, and the media. Everything else is mere distraction," Michael Wolff writes in The Hollywood Reporter. Perhaps Trump is so vague because he's just been called on and apparently hasn't done his homework. Read the entire profile of Trump in The Hollywood Reporter. Jeva Lange

The Universit of Oxford announced Saturday it will launch a new trial to test the COVID-19 vaccine it has developed in partnership with AstraZeneca on children between the ages of six of 17.

The two-dose Oxford-AstraZeneca vaccine is already in use in the United Kingdom, though the approval only people 18 and over can receive the shots as of now. Trial inoculations are expected to begin later this month, with around 300 volunteers enrolling to help determine efficacy and safety. This marks the first attempt by a coronavirus vaccine developer to test its candidate in young people, NBC News notes.

Prof. Andrew Pollard, the chief of investigator on the Oxford vaccine trial, acknowledged children are "relatively unaffected" by the novel coronavirus, but it's still "important to establish the safety and immune response" because "some children may benefit from the vaccine."

The Food and Drug Administration has yet to assess the Oxford-AstraZeneca vaccine for use in the United States. Read more at NBC News and BBC. Tim O'Donnell

The twists and turns of President Trump's Senate impeachment trial just kept coming on Saturday.

Earlier in the day, the Senate surprised everyone by voting to consider witness testimony, which likely would have extended the trial into next week, at least. There was reportedly a lot of confusion, and even some harsh exchanges, on the Senate floor in the wake of the vote, and reports suggested those in Trump's orbit were stunned at the last-minute development. His legal team, meanwhile, seemed prepared to call a host of witnesses to counter the Democratic House impeachment managers, who wanted to bring in Rep. Jaime Herrera Beutler (R-Wash.) to testify about a Jan. 6 phone call between Trump and House Minority Leader Kevin McCarthy (R-Calif.), the contents of which she said McCarthy relayed to her.

But it wasn't meant to be. During a brief recess the two sides reportedly reached a deal, and once the upper chamber reconvened Rep. Jamie Raskin (D-Md.) simply read Herrera Beutler's statement about the call. That was entered into the Senate record, no further witnesses will be called, and closing arguments are underway.

Democrats were quickly accused of caving despite seemingly having momentum on their side, even if Trump's acquittal remained the most likely outcome. It's unclear why exactly they didn't follow through, but attorney Daniel Goldman, the lead counsel for the House's first impeachment inquiry into Trump last year, said he was told that the impeachment managers weren't able to round up the witnesses they wanted, especially on short notice. Tim O'Donnell

Former President Donald Trump's impeachment trial likely will not end Saturday, as many expected, and it's unclear how long it will continue, raising questions about how the proceedings could affect President Biden's legislative agenda, especially in regards to a new COVID-19 relief bill.

There are no guarantees about how events will fold — the Senate's surprise vote Saturday morning to hear from witnesses in the trial is exhibit A — but, the upper chamber was scheduled to be on recess next week, either way. So, at least for the next several days, the trial won't officially be getting in the way of anything, though it could still sideline some potentially important discussions. Tim O'Donnell

As the Senate floor transformed into a state of confusion following the surprising vote to hear from witnesses in former President Donald Trump's impeachment trial, Sen. Ron Johnson (R-Wisc.) reportedly got into a heated discussion with his GOP colleague Sen. Mitt Romney (R-Utah), who along with four other Republicans joined Democrats in the 55-45 tally.

Johnson, like most everyone else, was apparently under the assumption the vote would go the other way, setting up a quick end to the trial on Saturday. But Democrats became more interested in hearing from witnesses after more details about a call between Trump and House Minority Leader Kevin McCarthy (R-Calif.) in the middle of the Jan. 6 Capitol riot emerged. And shortly after the Senate on Saturday morning, Rep. Jamie Raskin (D-Md.), a House impeachment manager, said he and the other managers wanted to hear from Rep. Jaime Herrera Beutler (R-Wash.), who described McCarthy's recounting of the call.

Trump was and still is headed toward acquittal, as it remains unlikely enough Republicans will be swayed by witnesses to reach the two-thirds majority required for conviction. For instance, it was reported earlier Saturday that Senate Minority Leader Mitch McConnell (R-Ky.), who was at least publicly on the fence, had told colleagues in an email that he was prepared to vote to acquit. It doesn't seem like that will change, since his reasoning was based on the fact that Trump is already out of office rather than on anything about Trump's alleged role, or lack thereof, on Jan. 6. Other lawmakers are expected to move forward with the same rationale. Tim O'Donnell

In what is widely considered a plot twist, the Senate voted 55-45 on Saturday morning to consider hearing from witnesses in former President Donald Trump's Senate impeachment trial.

The upper chamber was expected to vote against calling witnesses, which would have kept the trial on track for a quick verdict vote, but the timeline of the trial is now up in the air. Sens. Susan Collins (R-Maine), Lisa Murkowski (R-Alaska), Mitt Romney (R-Utah), and Ben Sasse (R-Neb.), joined their Democratic colleagues, and Sen. Lindsey Graham (R-S.C.) then flipped from a no to a yes vote, presumably because he wants to make the case for witnesses on behalf of the defense. Tim O'Donnell

Rep. Jaime Herrera Beutler (R-Wash.), one of the 10 House Republicans who voted to impeach former President Donald Trump, confirmed Friday night the contents of a phone call, new details of which were reported by CNN, between Trump and House Minority Leader Kevin McCarthy (R-Calif.) while the Jan. 6 Capitol riot was ongoing.

Herrera Beutler released a statement describing the conversation as it was relayed to her by McCarthy and calling on her colleagues, some of whom spoke anonymously to CNN, to come forward "if you have something to add." Herrera clarified that she has already publicly discussed McCarthy's recounting multiple times.

During the call, McCarthy reportedly urged Trump to "publicly and forcefully call off the riot," but Trump reportedly initially applied by claiming that antifa, not his supporters, were behind the breach. When McCarthy reportedly dismissed the idea, Trump reportedly replied, "Well, Kevin, I guess these people are more upset about the election than you are."

Per CNN, that reportedly sparked a shouting match between the two men, with McCarthy telling the then-president that rioters were breaking into his office through the windows. "Who the f--- do you think you are talking to?," McCarthy asked Trump, CNN reports. Herrera Beutler did not include that detail in her statement.

Sen. Sheldon Whitehouse (D-R.I.) tweeted late Saturday night that the newly-resurfaced reports should lead to a suspension of Trump's impeachment trial, so senators can do depose McCarthy under oath, but any alterations to the Senate's timetable seem unlikely at this point. Read more at CNN. Tim O'Donnell