Before the election, Trump worried publicly about his prospects among suburban voters following a dramatic swing for Democrats in 2018, said ABC's "This Week" Co-anchor Martha Raddatz.

While his win might not have been the landslide Biden was hoping for, one pattern the polls predicted did come true, FiveThirtyEight editor in chief Nate Silver said.

"He did really well in the suburbs."

"Believe it or not, Biden did a tiny bit worse than Hillary Clinton in the city of Philadelphia. He netted about 471,000 votes from it, as compared to 475,000 for her," Silver said while reviewing voting data in Pennsylvania. "But in the four suburban counties in the Philly metro area, Bucks, Chester, Delaware and Montgomery, Biden improved on Clinton's performance by a combined 105,000 votes.  That's enough to account for his entire margin over Trump in the Keystone State."

In Wisconsin, he said he saw a similar pattern for Biden, where a 25,000 vote improvement relative to Clinton was enough to account for his roughly 20,000 vote overall margin of victory there.

"I don't even need to tell you about Georgia. You can just look at the map to see how much the entire Atlanta metro area has turned blue," he said. "But in the five core counties in the Atlanta metro -- Fulton, DeKalb, Gwinnett, Cobb and Clayton -- Biden won by more than 700,000 votes, as compared to 470,000 for Hillary."

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'Those suburban votes were key to putting Biden over the top': Nate Silver

FiveThirtyEight’s Nate Silver discusses the impact of suburban voters on "This Week."

Though Trump is signaling he will leave the White House despite publicly fighting on, Washington Post opinion columnist Michele Norris said he will remain an important person in the party.

"He's now saying if the Electoral College approves Joe Biden, that he will leave. But will he ever really leave?" she said on ABC's "This Week" Sunday. "I mean, I think it's safe to assume he'll represent thunder at the fringe for years to come, that he will be an important person in the party, a greatly influential person in the party."

Retired Navy Adm. William McRaven said Sunday that he doesn't think the president-elect can get back into the Iran nuclear deal without some changes.

"There's been a lot of controversy and a lot of folks who don't like the JCPOA and I understand that," McRaven said on ABC's "This Week." "But the fact of the matter is the JCPOA, which probably going to give us, you know, 10 to 12 to 15 years before the Iranians could possibly have enriched enough uranium to build bomb."

Complicating matters is Friday's apparent assassination of one of Iran's most prominent scientists, Mohsen Fakhrizadeh. While no one has claimed responsibility for the killing, the incident has brought out a full response from Iran's top officials, including the country's foreign minister, Mohammad Javad Zarif, who pointed the finger at Israel.

"Now, of course, by attacking their nuclear scientist, by really escalating this effort, the Iranians I think are going to be more compelled to try to get a bomb quicker. This is going to complicate President Biden's efforts, diplomatic efforts," he told "This Week" Co-anchor Martha Raddatz on Sunday. "Now, again, from the Iranian standpoint, after President Trump pulled out of the JCPOA, I think they are going to be very, very reluctant to get into any agreements with the United States at this point. So, a President Biden will have a difficult challenge on his hand."

Another court ruling has gone against allies of the Trump campaign in their bid to halt certification of the 2020 presidential election in Pennsylvania, as the state's Supreme Court issued an order Saturday dismissing a recent court challenge focused on mail-in voting.

This election challenge was brought by U.S. Rep. Mike Kelly, a Republican, along with another GOP candidate for Congress, alleging that the state legislature had not legally passed the measure allowing for universal mail-in voting.

The plaintiffs called on the court to have Pennsylvania Secretary of State Kathy Boockvar cancel all mail-in ballots or, if not, to empower the state legislature to appoint new electors. A trial judge on Tuesday had imposed a temporary injunction to pause the election certification process until the question could be resolved. Boockvar's office brought the matter immediately to the state Supreme Court.

The Pennsylvania Supreme Court vacated the injunction on Saturday and dismissed the case with prejudice, meaning the GOP cannot bring it back.

-ABC News' Matthew Mosk and Alex Hosenball