By Trevor Hunnicutt and Steve Holland

WILMINGTON, Del./WASHINGTON (Reuters) – Democrat Joe Biden held a narrow lead over President Donald Trump in Wisconsin after officials completed their vote count and pulled further ahead in Michigan, even as the Republican incumbent’s campaign vowed to pursue a recount and a lawsuit to challenge the results in the two Midwestern battleground states.

Wisconsin and Michigan are critical in the race to the 270 electoral votes in the state-by-state Electoral College needed to win the White House. Trump won both states in his 2016 election victory. Losing them would greatly harm his quest for another four years in office.

Trump, who made attacking the integrity of U.S. elections a central campaign theme, in the early-morning hours falsely claimed victory in the election and made unsubstantiated allegations of electoral fraud. His campaign on Wednesday said it had filed a lawsuit seeking to stop the count in Michigan, asserting it had not been allowed to observe the opening of ballots.

Biden led by 38,000 votes out of more than 5 million ballots in Michigan.

“Michigan’s elections have been conducted transparently, with access provided for both political parties and the public, and using a robust system of checks and balances to ensure that all ballots are counted fairly and accurately,” Ryan Jarvi, press secretary to Democratic Michigan Attorney General Dana Nessel, said in a statement.

Wisconsin officials finished their tally at around midday after an all-night effort, showing Biden with a lead of just over 20,000 votes, or 0.6%, according to Edison Research. The Trump campaign immediately said it would request a recount, which is permitted under state law when the margin is below 1%.

CNN, Fox News and the Associated Press projected Biden as the winner in Wisconsin, though Edison Research, which provides voting data to the National Election Pool media consortium, has not announced a winner because of the pending recount.

Closely contested states including Michigan, Pennsylvania, Arizona, Nevada, Georgia and North Carolina were still counting votes, leaving the national election outcome still in doubt.

THE PANDEMIC EFFECT

Voting concluded as scheduled on Tuesday night, but many states routinely take days to finish counting ballots. There was a surge in mail-in ballots nationally amid the coronavirus pandemic.

Trump led in the two Southern states, Georgia and North Carolina, as well as in Pennsylvania. But if Trump loses Wisconsin and Michigan, he would have to win all three as well as either Arizona or Nevada, where Biden was leading in the latest vote counts.

At the moment, not including Wisconsin, Biden leads Trump 227 to 213 in Electoral College votes, which are largely based on a state’s population.

Biden led in Arizona, a battleground state with a high Latino population, which would make him only the second Democratic presidential candidate to win the state in 72 years. Trump won the state in 2016.

In Pennsylvania, Trump led by about 389,000 votes as officials gradually worked their way through millions of mail-in ballots, which were seen as likely to benefit Biden. Trump campaign manager Bill Stepien called the president the winner in Pennsylvania even though state officials had not completed the count.

In dueling conference calls with reporters earlier on Wednesday, officials from each campaign insisted their candidate would prevail.

“If we count all legal ballots, we win,” Stepien said, setting the stage for the post-election litigation over ballot counting.

Biden campaign manager Jennifer O’Malley Dillon told reporters the former vice president was on track to win the election, while senior legal adviser Bob Bauer said there were no grounds for Trump to invalidate lawfully cast ballots.

“We’re going to defend this vote, the vote by which Joe Biden has been elected to the presidency,” said Bauer, adding that the campaign’s legal team was prepared for any challenge.

Biden was expected to deliver an address later on Wednesday. The campaign also launched a new group, the Biden Fight Fund, to raise money for legal fights over the election.

Trump continued to make unsubstantiated attacks on the vote-counting process on Twitter on Wednesday, hours after he appeared at the White House and declared victory in an election that was far from decided. Both Facebook and Twitter flagged multiple posts from the president for promoting misleading claims.

“We were getting ready to win this election. Frankly, we did win this election,” Trump said before launching an extraordinary attack on the electoral process by a sitting president. “This is a major fraud on our nation. We want the law to be used in a proper manner. So we’ll be going to the U.S. Supreme Court. We want all voting to stop.”

Trump provided no evidence to back up his claim of fraud and did not explain how he would fight the results at the Supreme Court.

In the nationwide popular vote, Biden on Wednesday was comfortably ahead of Trump, with about 3 million more votes. Trump won the 2016 election over Democrat Hillary Clinton after winning crucial battleground states even though she drew about 3 million more votes nationwide.

The election uncertainty only added to the anxiety many Americans were feeling following a vitriolic campaign that unfolded amid a pandemic that has killed more than 233,000 Americans and left millions more jobless. The country has also grappled with months of unrest involving protests over racism and police brutality.

Biden’s hopes of a decisive early victory were dashed on Tuesday evening when Trump won the battlegrounds of Florida, Ohio and Texas. Among other undecided states, Nevada does not expect to update its vote count until Thursday, state officials said.

TEAMS OF LAWYERS

It was not clear what Trump meant by saying overnight that he would ask the Supreme Court to halt “voting.” The high court does not hear direct challenges but instead reviews cases that have worked their way up from lower courts.

Trump has repeatedly said without evidence that widespread mail-in voting would lead to fraud, although U.S. election experts say fraud is very rare.

Legal experts have said the election outcome could get bogged down in state-by-state litigation over a host of issues, including whether states can include late-arriving ballots that were mailed by Election Day. Both campaigns have marshaled teams of lawyers in preparation for any disputes.

The Supreme Court previously allowed Pennsylvania to move forward with a plan to count ballots mailed by Election Day that arrive up to three days later, but some conservative justices suggested they would be willing to reconsider the matter. State officials planned to segregate those ballots as a precaution.

The election will also decide which party controls the U.S. Congress for the next two years, and the Democratic drive to win control of the Senate appeared to be falling short. Democrats had flipped two Republican-held seats while losing one of their own, and five other races remained undecided – Alaska, Michigan, North Carolina and two in Georgia.

Trump’s strong performance in Florida, a must-win state for his re-election, was powered by his improved numbers with Latinos.

Edison’s national exit poll showed that while Biden led Trump among nonwhite voters, Trump received a slightly higher proportion of the nonwhite votes than he did in 2016. The poll showed that about 11% of African Americans, 31% of Hispanics and 30% of Asian Americans voted for Trump, up 3 percentage points from 2016 in all three groups.

(Reporting by Trevor Hunnicutt in Wilmington, Delaware, and Jeff Mason in Washington; Additional reporting by Jason Lange, Steve Holland and Susan Heavey in Washington, and Rich McKay in Atlanta; Writing by Joseph Ax; Editing by Paul Thomasch and Will Dunham)