Joseph R. Biden Jr. started election night with many paths to 270 electoral votes, but by Wednesday morning President Trump had won Florida, Ohio and Texas and was within striking distance of winning North Carolina.That left a diminished but still significant number of ways by which Mr. Biden could prevail, mostly clustered around recapturing Michigan, Wisconsin and Pennsylvania, the once-reliable “blue wall” states that Mr. Trump toppled four years ago.Here are the top scenarios remaining for Mr. Biden, as well as Mr. Trump, to win the 2020 election. The Biden scenarios presume that he wins Nevada, a blue state where he is narrowly ahead.One path involves Mr. Biden winning both Arizona and Georgia, Sun Belt states where he appears competitive with tens of thousands of votes left to be counted.Mr. Biden has the edge in Arizona, and a win there would take some pressure off him to rely entirely on the blue-wall states. He can afford to lose Pennsylvania if he wins Arizona, Michigan and Wisconsin.If Mr. Biden prevails in Georgia and Arizona, he can reach 270 electoral votes while losing Pennsylvania and Michigan or Wisconsin.Or he could become president simply by winning back Michigan, Wisconsin and Pennsylvania.In Georgia, where Mr. Trump holds a narrow lead with about 92 percent of the vote counted, a leak at a processing center in the central part of the state delayed the tabulation of some ballots for Atlanta and its suburban counties, which are seen as Democratic strongholds.Roughly 20 percent of the vote remained unreported as of 6 a.m. Wednesday in DeKalb County, a heavily Democratic suburb of Atlanta.“Joe Biden’s path is largely unchanged since he entered this race,” Guy Cecil, the chairman of Priorities USA, a leading Democratic super PAC, said early Wednesday. “There are still at least five competitive states giving him multiple paths to 270. It may take a couple of days to count the votes, and we may need to fight the Trump campaign in court, but Joe Biden remains the favorite.”Mr. Biden, appearing briefly before his supporters in Wilmington, Del., early Wednesday, said he was “feeling real good about Wisconsin and Michigan” and predicted a win in Pennsylvania, a central battleground that is notorious for its sluggish counting of ballots.“We believe we are on track to win this election,” he said.Mr. Trump’s victories in Florida, Ohio and Texas did not create a new path for him so much as close off new shortcuts by which Mr. Biden could have claimed victory on Election Day. In remarks made early Wednesday from the White House, the president was adamant that he would hold onto Georgia, North Carolina, Michigan, Wisconsin and Pennsylvania — all states with significant percentages of ballots left to count.“We don’t need all of them” to win, he said.His last chance for a flip is Nevada, which was expected to be a tight race, but one generally favoring Mr. Biden.Otherwise, Mr. Trump’s path to winning a second term depends on holding onto the battleground Great Lakes states he won in 2016 and on retaining Georgia.Updated Nov. 4, 2020, 6:08 a.m. ET“Trump’s path is exactly the same as it was in 2016,” said Alex Conant, a Republican strategist who is a veteran of Senator Marco Rubio’s campaigns. “He needs to overperform in some traditionally blue states. Trump wins when the voters Democrats take for granted no longer reliably vote for Democrats.”In Wisconsin, Mr. Biden was running well ahead of Hillary Clinton’s 2016 margins in Waukesha County, a Milwaukee suburb, and Dane County, home to the liberal city of Madison. The Milwaukee turnout appeared to be lower than in 2016, a troubling possibility for Mr. Biden given the city’s heavily Democratic tilt.Still, Democrats were confident that the final vote tally would favor Mr. Biden.“I think if you look at what’s counted and what is not counted, Biden is almost assuredly going to win Wisconsin,” said Sachin Chheda, a Democratic strategist in Milwaukee.And then there is Nebraska, one of two states, along with Maine, that split their electoral votes by congressional district. Mr. Biden won the state’s Second Congressional District, which includes Omaha. The Nebraska Democratic Party chairwoman, Jane Kleeb, declared victory early Wednesday.“Omaha is now Joe-maha,” she said.Because Mr. Biden won that lone Nebraska electoral vote, he could secure the presidency by winning Arizona, Michigan and Wisconsin — regardless of the result in Pennsylvania.