Biden takes lead in Pennsylvania and Georgia as nation awaits a winner

Mr. Biden had already begun to project the image of a man preparing to assume the mantle of office, meeting on Thursday with his economic and health advisers to be briefed on the coronavirus pandemic.

Speaking briefly to reporters in Wilmington, Del., Mr. Biden urged the public to show a “little patience” as the vote counting in battleground states stretched into a third day.

“Democracy,” he said, “can sometimes be messy.”

Mr. Biden’s appeal to let the process play out contrasted with that of Mr. Trump, who took the lectern in the White House briefing room to falsely claim that the election was riddled with fraud, as part of an elaborate coast-to-coast conspiracy by Democrats, the news media and Silicon Valley to deny him a second term.

As the number of outstanding ballots slowly dwindled, Mr. Trump was left increasingly with only legal challenges to forestall defeat, while Mr. Biden was betting on the steady accumulation of mail-in ballots to keep him on top in Pennsylvania. Georgia, which has not elected a Democrat since Bill Clinton in 1992, was headed for a photo finish that could supply an extra cushion of electoral votes to Mr. Biden.

Inside the candidates’ campaign war rooms, staffers were briefed by their field operations to see where the outstanding votes were and how they would break for the candidates.

In Georgia, Mr. Biden’s total vaulted above Mr. Trump’s around 5 a.m., giving the former vice president a 917-vote lead.

But if the eastern battlegrounds were trending toward Mr. Biden, the Trump campaign drew some comfort from the West.

In Arizona, the continuing count whittled Mr. Biden’s early lead in the state to roughly 47,000 votes. After a delay in counting the remaining ballots from Maricopa County early Thursday, election officials continued to plow through tens of thousands of ballots from Phoenix and its sprawling suburbs. In Nevada, Mr. Biden clung to a lead of more than 11,000, with absentee ballots left to count in vote-rich Clark County, which includes Las Vegas.

Still, Mr. Biden’s victory in the Midwestern battleground states of Michigan and Wisconsin put him in a strong position, with multiple paths to victory, depending on what happens in the states yet to be called. Mr. Trump needed a victory in Pennsylvania.

The process was agonizing for partisans on both sides, though for the most part, fears of widespread unrest did not materialize. Officials reported few instances of problems with the voting-counting process.

The candidates’ differing reactions hinted at how they are likely to handle the coming days and weeks as the counting gives way to legal challenges, calls for recounts and a potentially turbulent transition.

Mr. Biden’s pivot to policy issues seemed intended to create an air of inevitability about his victory. His briefing on the pandemic was a reminder that the United States recorded a record 121,200 new infections on Thursday.