WILMINGTON, Del. (AP) — In a time of plague and raw division, President-elect Joe Biden appealed for unity Wednesday in a Thanksgiving-eve address to the nation asking Americans to "steel our spines" for a fight against the coronavirus that he predicted would continue for months.

But even as he implored Americans to join in healing and common purpose, President Donald Trump asserted that the election should be overturned, a futile call but one that stokes the divisions Biden is trying to overcome.

With COVID-19 cases surging nationwide, Biden called on Americans to take precautions to try to stem the tide of the virus, by wearing masks and practicing social distancing. While he said the federal government has "vast powers" to combat the virus, "the federal government can't do it alone."

"Each of us has a responsibility in our own lives to do what we can to slow the virus," he said in remarks in Wilmington.

Biden said that, until there's a vaccine, wearing masks, social distancing and limiting the size of gatherings "are our most effective tools to combat the virus." But he pledged that from the start of his presidency, "we will take steps that will change the course of the disease," including increasing testing, providing more protective gear and clearer guidance for businesses and schools to reopen.

And he said that he himself was taking precautions around Thanksgiving and eschewing his traditional large family gathering, instead spending the holiday with just his wife, daughter and son in law.

"This is the moment when we need to steel our spines, redouble our efforts and recommit ourselves to this fight," Biden said. "We're all in this together."

But Trump stoked the embers of his flailing effort to upend the election results as his lawyer, Rudy Giuliani, and other members of his legal team met Pennsylvania Republican state senators in Gettysburg. There, they again aired grievances about the election and repeated allegations of Democratic malfeasance that have already disintegrated under examination by courts.

Trump joined the meeting from the Oval Office, asserting: "This was an election that we won easily. We won it by a lot." In fact the election gave Biden a clear mandate and no systemic fraud has been uncovered.

In his remarks in Wilmington, Biden made passing reference to Trump's refusal to concede, declaring "our democracy was tested this year" but "the people of this nation are up to the task."

"In America, we have full and fair and free elections, and then we honor the results," he said. "The people of this nation and the laws of the land won't stand for anything else."

He also offered an optimistic vision, calling on Americans to "dream again" and predicting that "the 21st century is going to be an American century."

Biden's remarks came as COVID-19 cases are surging nationwide.  Hospitalizations, deaths and the testing positivity rate were also up sharply as the nation approached Thanksgiving, and public health experts have warned that the large family gatherings expected for the holiday are likely to extend and exacerbate the surge.

Biden has said turning the tide of the pandemic will be the top priority of his administration once he takes office in January, and he's made multiple public remarks urging Americans to embrace mask-wearing and social distancing guidelines to combat the spread. The Democratic president-elect formed a coronavirus advisory board of scientists, doctors and public health experts, and he plans to establish a COVID-19 coordinator in the White House to lead his administration's response.

This week, however, Biden focused beyond the crisis stateside and unveiled his national security team on Tuesday, including his nominees for secretary of state, director of national intelligence and U.S. ambassador to the United Nations. Drawing implicit contrasts with President Donald Trump throughout the event, Biden said that the team "reflects the fact that America is back, ready to lead the world, not retreat from it." He's also expected to name Janet Yellen as treasury secretary in the coming weeks.

The president-elect's team has also begun the next phase of its transition preparations after the Trump-appointed head of the General Services Administration declared Biden the "apparent winner" of the election, removing a major roadblock to cooperation between Biden's staff and their counterparts in the Trump administration.

Trump has refused to concede the election, and his campaign continues to pursue legal challenges to the vote in some states. But the GSA's ascertainment of Biden's win means the transition can proceed regardless of the Republican president's resistance.

For the next few days, Biden plans to spend some time focused on his family. He's traveling with his wife, Jill, to Rehoboth Beach, the small Delaware beach town where the two have a vacation home. That's where they'll host their daughter and son-in-law for Thanksgiving dinner. Biden is expected to stay through the weekend in Rehoboth, before returning to Wilmington for further work on the transition.