"I think the obvious answer is no. But I do think he has above average chances of having a successful first year or two in office if he can get the COVID pandemic under control," FiveThirtyEight's Nate Silver said in response to the question, "Can President Joe Biden unite the country?"

“He set a goal of 100 million shots in his first 100 days … that’s a floor, it’s not a ceiling,” Biden’s nominee for Surgeon General Vivek Murthy says when pressed by ABC News Chief Anchor George Stephanopoulos on whether the Biden administration’s vaccination plan is ambitious enough.

Sunday on ABC's "This Week," Stephanopoulos also asked Murthy if he is confident the U.S. can meet the goal of opening most elementary schools in the first 100 days of the Biden administration.

"That’s a very important goal," Murthy responded. "It’s going to take a lot of work."

National security adviser Jake Sullivan spoke with his Israeli counterpart Saturday and expressed the president's commitment to Israel's security.

Sullivan also discussed building on Israel's normalization arrangements with UAE, Bahrain, Sudan and Morocco -- negotiated under the Trump administration, according to a statement from NSC Spokesperson Emily Horne.

The president has also been making calls to officials from around the world, speaking with the leaders of Canada, Mexico and the U.K.

-ABC News' Molly Nagle

Defense Secretary Lloyd Austin has given his senior leaders two weeks to send him reports on sexual assault prevention programs in the military in his first directive since taking office, according to the Associated Press.

Austin's directive calls for his senior leaders to submit sexual assault and harassment measures they have taken in the past year and to detail which initiatives worked and which did not, as well as including data over the past decade about efforts they have taken to support sexual assault and harassment victims.

“Include in your report the consideration of novel approaches to any of these areas,” he said, adding that “we must not be afraid to get creative.”

Austin’s directive is the first step in a commitment that he made during his confirmation hearing in front of U.S. senators last week when we promised to address the issue of sexual assault and harassment in the military head on.

“This is a leadership issue,” Austin said in his two-page memo. “We will lead.”

In his confirmation hearing, senators pointedly asked what Austin planned to do about the issue.  Senator after senator demanded to know what Austin planned to do about the problem, which defense and military leaders have grappled with for years as reports of sexual assaults, according to the Associated Press, have steadily gone up since 2006, including a 13% jump in 2018 and a 3% increase in 2019.

Said Austin: “This starts with me and you can count on me getting after this on Day One.”

In his appearance on ABC's "This Week" Sunday, Biden’s nominee for Surgeon General Vivek Murthy said that when it comes to meeting the goal for 100 million vaccines in the first 100 days of the president's administration, there are things that could go right or wrong.

"I think President Biden fully understands there's a larger goal here, as we all do, which is that we've got to vaccinate as many Americans as possible. And that's going to take a lot of work, work dispelling this disinformation, working on the supply, increasing distribution channels," he told ABC News Chief Anchor George Stephanopoulos. "And that's some of what the vaccine plan that he announced over the last week is intended to -- to achieve."

Stephanopoulos pressed Murthy on whether there are ways to increase the supply and equitably distribute the vaccines.

"It appears, at least in these first vaccines that have gone out, they've been going largely to wealthier areas of the country, largely to whiter areas of the country," Stephanopoulos said.

"Well, it's the right question, George, because success has to be gauged not just by the number of vaccines we deliver but also by how fairly we deliver those vaccines -- how equitably we deliver them," he said in response. "What we've got to do here is not just, again, increase supply, which we can do using the Defense Production Act ... but we've also got to set up the kind of distribution channels, like mobile units, like strategically placed community vaccination centers, that can reach people who traditionally are hard to reach and don't have access to health care."

He added, "We have got to track our progress. We have got to make sure that we have data on where the vaccine is being administered, so that we can ensure that it, in fact, is being distributed equitably."