WILMINGTON, Del. — Joe Biden used his first nation­al address as pres­i­dent-elect to vow to heal a deeply divid­ed nation, declar­ing it was time to “let this grim era of demo­niza­tion in Amer­i­ca begin to end” and reach­ing out to the mil­lions of peo­ple who vot­ed against him to say, “Let’s give each oth­er a chance.”

His calls for rec­on­cil­i­a­tion at a Sat­ur­day evening vic­to­ry cel­e­bra­tion came even as Pres­i­dent Don­ald Trump con­tin­ued to argue that the elec­tion had been stolen from him, an indi­ca­tion that the divi­sive pol­i­tics that have gripped the U.S. over the past four years are far from over.

It also sug­gest­ed that even as Biden seeks to build out a gov­ern­ment dur­ing his tran­si­tion to the pres­i­den­cy, the pres­i­dent has lit­tle inter­est in help­ing him do so.

“For all those of you who vot­ed for Pres­i­dent Trump, I under­stand the dis­ap­point­ment,” Biden said dur­ing a dri­ve-in event in Wilm­ing­ton, Delaware. “It’s time to put away the harsh rhetoric, low­er the tem­per­a­ture, see each oth­er again.”

Biden heads into his first full day as pres­i­dent-elect on Sun­day with key staffing deci­sions to make as the coro­n­avirus rages. The always-fren­zied 10-week tran­si­tion peri­od before Inau­gu­ra­tion Day on Jan. 20 already has been short­ened by the extra time it took to deter­mine the win­ner of Tuesday’s election.

The sec­ond Catholic to be elect­ed pres­i­dent, Biden planned to attend church at St. Joseph on the Brandy­wine near his home in Wilm­ing­ton, as he does near­ly every week. He began Elec­tion Day with a vis­it to the church and the grave of his son, Beau, a for­mer Delaware attor­ney gen­er­al who died of brain can­cer in 2015.

His top pri­or­i­ty in the tran­si­tion is expect­ed to be quick­ly nam­ing a chief of staff. Biden sug­gest­ed dur­ing the cam­paign that his first call after being elect­ed would be to Dr. Antho­ny Fau­ci, the nation’s top infec­tious dis­ease expert, but his advis­ers have not said whether the two have spo­ken yet.

Biden said Sat­ur­day that he would announce a task force of sci­en­tists and experts Mon­day to devel­op a “blue­print” to begin beat­ing back the virus by the time he assumes the pres­i­den­cy. He said his plan would be “built on bedrock sci­ence” and “con­struct­ed out of com­pas­sion, empa­thy and con­cern.” A for­mer sur­geon gen­er­al, Vivek Murthy, and a for­mer Food and Drug Admin­is­tra­tion com­mis­sion­er, David Kessler, will lead the task force.

This com­ing week, Biden will launch his agency review teams — the group of tran­si­tion staffers that have access to key agen­cies in the cur­rent admin­is­tra­tion to smooth the trans­fer of pow­er. The teams will col­lect and review infor­ma­tion such as bud­getary and staffing deci­sions, pend­ing reg­u­la­tions and oth­er work in progress from cur­rent staff at the depart­ments to help Biden’s team pre­pare to transition.

Biden was on track to win the nation­al pop­u­lar vote by more than 4 mil­lion, a mar­gin that could grow as bal­lots con­tin­ue to be count­ed. He made Trump the first incum­bent pres­i­dent to be denied a sec­ond term since Repub­li­can George H.W. Bush lost to Bill Clin­ton in 1992.

His run­ning mate, Sen. Kamala Har­ris, used her first address as vice pres­i­dent-elect to show­case her his­to­ry-mak­ing place as the first Black woman to become vice pres­i­dent, an achieve­ment that comes as the U.S. faces a reck­on­ing on racial jus­tice. The Cal­i­for­nia sen­a­tor is also the first per­son of South Asian descent elect­ed to the vice pres­i­den­cy and the high­est-rank­ing woman ever to serve in government.

“While I may be the first woman in this office, I will not be the last,” Har­ris said in her speech Sat­ur­day night.

To win, Biden suc­cess­ful­ly uni­fied dif­fer­ent wings of the Demo­c­ra­t­ic Par­ty around their uni­ver­sal loathing of Trump, gar­ner­ing sup­port from pro­gres­sive insur­gents and estab­lish­ment mod­er­ates alike.

“The par­ty came togeth­er to defeat Don­ald Trump,” said Bri­an Lemek, a long­time pro­gres­sive fundrais­er and exec­u­tive direc­tor of Brady PAC, which invest­ed $6 mil­lion on 2020 can­di­dates sup­port­ing gun vio­lence pre­ven­tion efforts and vot­ing rights. “His main job right now, we all think, is to heal the nation.”

Biden senior advis­er Ted Kauf­man said the tran­si­tion team will focus on the “nuts and bolts” of build­ing the new admin­is­tra­tion in com­ing days. He said Biden plans to speak to leg­isla­tive lead­ers and gov­er­nors from both parties.

Biden may not make top Cab­i­net choic­es for weeks. But he built his pres­i­den­tial run around bipar­ti­san­ship and he has spent the days since Tuesday’s elec­tion pledg­ing to be a pres­i­dent for all Amer­i­cans. That sug­gests he could be will­ing to appoint some Repub­li­cans to high-pro­file admin­is­tra­tion positions.

Many for­mer Repub­li­can office­hold­ers broke with Trump to endorse Biden’s cam­paign. His selec­tion of some of them to join the new gov­ern­ment could appease Sen­ate Repub­li­cans, who may have to con­firm many of Biden’s choic­es for top jobs. The GOP could retain con­trol of the cham­ber after two spe­cial elec­tions in Geor­gia on Jan. 5.

Still, too much across-the-aisle coop­er­a­tion could draw the ire of pro­gres­sives. Some already wor­ry that unco­op­er­a­tive Sen­ate Repub­li­cans could force Biden to scale back his ambi­tious cam­paign promis­es to expand access to health care and lead a post-pan­dem­ic eco­nom­ic recov­ery that relies on fed­er­al invest­ment in green tech­nol­o­gy and jobs to help com­bat cli­mate change.

“I think there will be a huge mis­use of the word ‘uni­ty’ to imply that we need to water down the ideas that Joe Biden just cam­paigned on,” said Adam Green, co-founder of the Pro­gres­sive Change Cam­paign Com­mit­tee. He said the coun­try was more unit­ed around bold solu­tions to big prob­lems than small-scale efforts.

Biden’s efforts at bipar­ti­san rec­on­cil­i­a­tion, mean­while, could still be derailed by Trump’s refus­ing to con­cede the pres­i­den­tial race. It wasn’t clear if Biden and Trump would meet in com­ing days, as is the mod­ern tra­di­tion. Biden deputy cam­paign man­ag­er Kate Bed­ing­field told CNN late Sat­ur­day that there’s been no con­tact between Trump’s team and Biden’s.

Symone Sanders, a Biden cam­paign spokes­woman, said “Don­ald Trump does not get to decide the win­ner of elections.”

“The peo­ple decide, vot­ers in the coun­try decide,” Sanders said. “And vot­ers have made their choice very clear.”

Trump start­ed his Sun­day morn­ing by retweet­ing sup­port from a promi­nent legal expert call­ing for review of the balloting.

Sen. Mitt Rom­ney, R‑Utah, said Trump had a right to pur­sue recounts and legal chal­lenges. But he not­ed that those efforts will unlike­ly change the out­come and he urged the pres­i­dent to dial back his rhetoric.

“I think one has to be care­ful in the choice of words. I think when you say the elec­tion was cor­rupt or stolen or rigged that that’s unfor­tu­nate­ly rhetoric that gets picked up by author­i­tar­i­ans around the world. And I think it also dis­cour­ages con­fi­dence in our demo­c­ra­t­ic process here at home,” Rom­ney told NBC’s “Meet the Press.”