Joseph R. Biden Jr. gained ground in Pennsylvania, Nevada and Georgia on Thursday as the slow-moving vote count in those contested battleground states moved him closer to capturing an electoral majority and defeating President Trump.
As an anxious country waited to learn the winner, the two candidates emerged toward day’s end to make remarks that were dramatically different in tone and content.
In a brief appearance before reporters in Wilmington, Del., Mr. Biden said he remained confident that he would ultimately prevail but did not lay claim to the White House.
“Democracy’s sometimes messy,” said Mr. Biden, who remained ahead in Arizona on Thursday night but lost some ground there. “It sometimes requires a little patience as well. But that patience has been rewarded now for more than 240 years with a system of governance that’s been the envy of the world.”
He urged calm and emphasized that “each ballot must be counted.”
Hours later, in a stunning appearance in the White House briefing room, Mr. Trump lied about the vote-counting underway in several states, conjuring up a conspiracy of “legal” and “illegal” ballots being tabulated and claiming without evidence that states were trying to deny him re-election.
“They’re trying to steal an election, they’re trying to rig an election,” the president said from the White House briefing room. He also baselessly suggested nefarious behavior in Philadelphia and Detroit, cities that he called “two of the most corrupt political places.”
Mr. Trump’s remarks, mostly read off notes, were at times more valedictory than defiant. Far from insisting that he would stay in power, he used much of his appearance to complain about pre-election polls, demonize the news media and try to put the best face on Tuesday’s results, trumpeting his party’s congressional gains. He did not take questions from reporters.
For all of his complaints, Mr. Trump has only himself and his own party to blame for the delayed vote count in a number of states.
State and local Republican officials refused to let localities tally mail-in votes before Tuesday in some states. And because of Mr. Trump’s monthslong attacks on mail ballots, more Democrats than Republicans voted in that fashion, which has allowed Mr. Biden to pick up the bulk of the votes arriving in the mail.
In his speech, Mr. Trump expressed no concern about the protracted vote count in Arizona, a state where he has been cutting into Mr. Biden’s lead as more ballots are tabulated.
Republican leaders offered no immediate response to Mr. Trump’s remarks, but a small group of maverick lawmakers in the party denounced his comments, seeking to reassure voters that there was no reason to believe the integrity of the election had been undermined.
Representative Adam Kinzinger, Republican of Illinois and a frequent critic of Mr. Trump, offered the sharpest rebuke, saying “this is getting insane” and demanding that the president stop “spreading debunked misinformation.”
Larry Hogan, the Republican governor of Maryland, wrote, “There is no defense for the President’s comments tonight undermining our Democratic process.”
Yet there were also Republican lawmakers who rushed to Mr. Trump’s defense, siding with him in falsely asserting that the vote counting was illegal and Democrats were trying to cheat. “Radical Dems tried to do away with law and order and are now trying to do away with law and order at the ballot box,” wrote Representative Roger Williams of Texas.
With the world watching to see if one of the most unusual presidencies in the country’s history was coming to an end, America’s patchwork of electoral laws created a confusing and angst-inducing day for both parties, to say nothing of millions of Americans eager for the campaign’s conclusion.
Mr. Biden’s advantage in Arizona, a state The Associated Press has already called for the former vice president, narrowed as thousands of votes were tabulated. But in Georgia and Pennsylvania, Mr. Trump saw his early advantage dwindle as mail-in ballots were counted.
Until Mr. Trump’s remarks on Thursday night, he had not appeared in public since he used a middle-of-the-night appearance Wednesday to insist he had already won. But he has posted angry Twitter messages, and he continued to do so Thursday.
“All of the recent Biden claimed States will be legally challenged by us for Voter Fraud and State Election Fraud,” he said in one message, without elaborating on what precisely that would involve. “STOP THE COUNT!” he exclaimed in another tweet.
Rebuking the president, Twitter labeled some of the messages “disputed” and said they “might be misleading about an election or other civic process.”
In any event, stopping the count now would only ensure that Mr. Biden wins the presidency, because he is leading in Arizona and Nevada — states that together would give him 270 electoral votes.
The presidential contest was not the only tight race drawing attention. A key Georgia Senate race that could decide the majority in the chamber grew even closer as Senator David Perdue, a Republican, saw his vote share slip under 50 percent in his race against Jon Ossoff, a Democrat. If neither wins a majority, the race would head to a January runoff, setting up the prospect of a hotly contested battle for two Senate seats in Georgia. A runoff is already planned in the special election for the state’s other seat.
On Thursday, an array of Mr. Trump’s political surrogates fanned out to some of the contested states to rally his supporters. And the president’s lawyers filed lawsuits in several states questioning the integrity of the vote count in hopes of slowing down the process.
He suffered two legal setbacks on Thursday when judges in Georgia and Michigan ruled against his campaign. But Mr. Trump notched a minor victory in Pennsylvania when a state appellate court acceded to its request to force Philadelphia election officials to grant its election observers better access to areas where workers are counting ballots.
With the counting proceeding slowly in the West, much of the focus on Thursday fell on Pennsylvania, where a victory would deliver Mr. Biden the presidency no matter the results in the other states. The top election official in the state said on Thursday evening that counties were “still counting” and did not offer any timetable for when the tally would be complete.
Mr. Trump’s lead in the state, about 26,000 votes as of 10:50 p.m. Eastern, was shrinking as mail-in ballots were counted in the heavily Democratic cities and suburbs.
The two parties held dueling news conferences in Philadelphia early in the day, with Mr. Trump’s supporters insisting his lead would hold statewide and the city’s Democrats, led by former Representative Robert A. Brady, unveiling an analysis of the remaining vote count that concluded Mr. Biden would win Pennsylvania convincingly.
In Georgia, the counting of ballots in numerous counties continued to erode Mr. Trump’s advantage in the traditionally Republican state: By Thursday night, he was leading by about 1,800 votes out of nearly five million cast.
Tens of thousands of ballots remained to be counted in the state late in the day, including many in Chatham County, a Democratic-leaning county along the Georgia coast that is home to Savannah, and many thousands more from Atlanta-area counties that also lean Democratic.
Georgia’s Republican Party has said it plans to bring up to a dozen lawsuits in the state.
In Arizona, Mr. Biden’s lead was down to about 46,000 votes, significantly less than it was on election night. There are several hundred thousand ballots left to count, with many coming from Phoenix’s Maricopa County, which was expected to release an update on Thursday evening.
Adrian Fontes, the Democrat who oversees elections in Maricopa County, home to Phoenix, said that officials would continue to release updates daily at 9 p.m. Eastern, including over the weekend.
“We’re plugging along and making it happen,” Mr. Fontes said.
The vote count in Maricopa has grown tense, however, since several armed protesters showed up at the county office Wednesday night. On Thursday afternoon, about 200 supporters of Mr. Trump also gathered in front of the headquarters of the Arizona Republican Party after a protest earlier in the day involving about 50 Trump supporters dissipated in front of City Hall in Phoenix.
Some in the crowd held signs reading “Don’t Steal Elections,” “Shame on Fox News” and “Recall Fontes.” (Fox News called Arizona for Mr. Biden on Tuesday night, inflaming Trump supporters.)
Mr. Biden led by just over 11,000 votes in Nevada, but local officials in Las Vegas announced Thursday that 51,000 ballots from Clark County there were being tallied and would be announced Friday. Mr. Biden was winning the county by about eight percentage points. If he wins the bulk of the new votes, it would make it almost impossible for Mr. Trump to take the state, because about 70 percent of Nevada’s voters live in Clark County.
As part of the effort to sow doubt on the state’s election, Mr. Trump’s Nevada state director sent a letter to supporters on Thursday asking them “to go on camera/on the record with the issues they faced voting this election” to “expose issues we are seeing at polling locations/clerks offices.”
For its part, publicly and privately, the Biden campaign spent much of Thursday trying to tamp down expectations about the certainty of results in individual states, even as his supporters were on edge when the margins turned out to be far closer than many had expected.
In a briefing with reporters, Jennifer O’Malley Dillon, Mr. Biden’s campaign manager, acknowledged that his leads in Arizona and Nevada might tighten or otherwise fluctuate. It was a departure from her position the day earlier when she referred to a “historic victory in a place like Arizona,” though she still expressed optimism about victories in both states.
“We do expect, similar to Nevada, that some of the margin will continue to close today,” she said of Arizona, a state she has focused on for months. “The story of Arizona is one where Joe Biden is going to win, but it’s going to take us time and patience as we go through the counting.”
“The story of today,” she said at another point, “is going to be a very positive story for the vice president, but also one where folks are going to need to stay patient and stay calm.”
Reporting was contributed by Catie Edmondson in Washington, Nick Corasaniti in Philadelphia, Richard Fausset in Atlanta, and Jennifer Medina and Simon Romero in Phoenix.