The leader of the agency responsible for approving the immunization, Dr. Stephen Hahn, maintained Sunday that the authorization was made as quickly as possible, despite claims to the contrary by President Donald Trump.

In an interview with Fox News Saturday, Trump, after seeming to take credit for the speed of the vaccine's development, said that the Food and Drug Administration could have authorized the shot for emergency use "last week."

"We do not feel that this could have been out a week earlier," Dr. Stephen Hahn, the FDA commissioner, said on ABC's "This Week." "We went through our process. We promised the American people that we would do a thorough review of the application and that's what we did. We followed our process."

Full story here.

- Adam Kelsey

New Jersey will begin giving its health care workers the COVID-19 vaccine Tuesday morning at University Hospital in Newark, the state's governor said on ABC's "This Week" Sunday.

"The first batch of 76,000, split the majority toward health care workers but a good slug toward our long-term care residents and staff, and then with each ensuing week those are the two top priorities," Gov. Phil Murphy, D-N.J., told "This Week" co-anchor Martha Raddatz.

"It'll take us a number of weeks as you can imagine to work through the entire populations in both of those groups, but it's gonna be a big day on Tuesday morning in Newark," he added.

Full story here.

- Adia Robinson

Another Cybersecurity and Infrastructure Security Administration official is stepping down at the end of the week.

Matt Masterson, a top official at CISA, who was instrumental in securing the 2020 election, confirmed on Twitter he's leaving for a position at Stanford University.

Masterson tweeted that he can't wait to work with the staff and students at Stanford.

The news comes after former CISA Director Chris Krebs was fired via tweet by President Donald Trump in November. The president bristled at Krebs' assertion that there was no evidence of fraud in the election.

Bryan Ware, another of Krebs' top lieutenants at the agency, stepped down just before his boss was fired last month.

-ABC News' Luke Barr

Sparks flew Saturday as justices on the Wisconsin Supreme Court questioned Jim Troupis, a lawyer for the Trump campaign who argued that the state should throw out 220,000 votes from Dane and Milwaukee counties.

Justice Jill Karofsky lit into Troupis under 10 minutes into the hearing, accusing the campaign of trying to disenfranchise Black voters.

“In your lawsuit, what you have done here, is you have targeted the vote of almost a quarter of a million people, a quarter of a million people not statewide in Wisconsin, but … in two of our 72 counties, two counties that are targeted because of their diverse populations, because they're urban; I presume because they vote Democratic. This lawsuit, Mr. Troupis, smacks of racism,” Karofsky said.

Troupis and the Trump campaign argued that the court should throw out four categories of votes they said did not follow state statute, including absentee ballots delivered in person at a “Get Out the Vote” event in a park, ballots applied for with a specific mail-in form, ballots missing the address of a signed witness and ballots applied for by “indefinitely confined voters.”

As the hearing continued, Justice Rebecca Dallet once again homed in on the demographic makeup of Milwaukee and Dane counties, noting that the Trump campaign was “not asking … to throw out votes in any other county.” Troupis became defensive, telling the justices that the Biden campaign could have asked for the recount to encompass the whole state.

“You made a statement, as if this was a choice based on criteria that simply are not true,” Troupis said before Dallet jumped on him.

“Who chooses which counties to ask for a recount?” Dallet asked.

Troupis responded “the candidate,” to which Dallet noted the president “had a choice when it came to the recount of which counties. … He chose to only challenge votes in the most urban, non-white, largest counties that voted overwhelmingly for Joe Biden.”

-ABC News' Alex Hosenball and Matt Mosk

Ahead of Monday’s meeting of Michigan’s 16 electors at the state Capitol in Lansing, officials announced the state legislature's office buildings will be closed due to "credible threats of violence."

The decision to close the state House and Senate offices — while the presidential electors convene in the Senate chamber to cast their votes for President-elect Joe Biden, who carried the state by more than 154,000 votes — came from a recommendation from law enforcement, officials said.

But the decision was not motivated by anticipated protests outside the capitol, according to a statement from Amber McCann, a spokesperson for Senate Majority Leader Mike Shirkey.

"The Senate has closed its own workspaces tomorrow based upon recommendations from law enforcement. The decision was not made because of anticipated protests, but was made based on credible threats of violence," McCann said late Sunday night, without adding any details about the threats.

"Senate leadership does not have the authority to close the Capitol. That decision is made by the Capitol Commission," she continued.

A spokesperson for Lee Chatfield, Speaker of the Michigan House, confirmed that the closures apply to the lower chamber as well.

Amid the "safety concerns," state lawmakers will be working remotely on Monday, a Democratic member of the House tweeted.

-ABC News' Kendall Karson