US President-elect Joe Biden has unveiled officials for six important posts, as he prepares to take office.
"America is back", he said, and "ready to lead the world, not retreat from it".
If confirmed, Avril Haines will be the first female director of national intelligence and Alejandro Mayorkas the first Latino homeland security boss.
Donald Trump has agreed transition moves must start and Biden will now get a top secret intelligence brief.
However, the sitting president still refuses to admit defeat, repeating unsubstantiated claims that the 3 November vote was "rigged".
As well as getting the Presidential Daily Brief - an update on international threats and developments - Biden can now access key government officials and millions of dollars in funds as he prepares to take over on 20 January.
CNN reported Biden's team was now in contact with all federal agencies.
On Tuesday, Governor Tom Wolf said he had certified Biden's victory in Pennsylvania, a key swing state. Another, Michigan, certified the same outcome on Monday.
Who are his picks?
Biden presented six key figures on Tuesday:
- Antony Blinken, Secretary of state. Blinken said the US would soon "with equal measures of humility and confidence" restore its relationships with other countries
- John Kerry, Climate change envoy. He was one of the leading architects of the Paris climate agreement, from which President Trump withdrew. Kerry said the world must "come together to end the climate crisis"
- Avril Haines, Director of national intelligence. Biden said: "I picked a professional... a fierce advocate for telling the truth".
- Alejandro Mayorkas, Secretary of homeland security. Mayorkas said the department had "a noble mission, to help keep us safe and to advance our proud history as a country of welcome"
- Jake Sullivan, White House national security adviser. Sullivan praised his boss, saying he had taught him much about statecraft, but also "most importantly about human nature"
- Linda Thomas-Greenfield, US ambassador to the UN. She said she brought her southern Louisiana roots to her job, calling it "a cajun spin" on "gumbo diplomacy"
One choice that is expected but has not been announced yet is former Federal Reserve chair Janet Yellen as treasury secretary
Most of the picks, although not Kerry or Sullivan, will need confirmation by the Senate. Rejection of a nominee is rare. The last was in 1989, although some nominees have withdrawn from consideration.
What did Biden say?
Speaking in Wilmington, Delaware, the president-elect highlighted the need to rebuild alliances, as well as tackling coronavirus and climate change.
World leaders, he suggested, were "looking forward to the United States reasserting its historic role as a global leader over the Pacific, as well as the Atlantic, all across the world".
Speaking to NBC News, he said: "This president, President Trump, has changed the landscape. It's become America first, America alone. We find ourselves in a position where our alliances are being frayed."
On Monday, New Zealand Prime Minister Jacinda Ardern revealed she had spoken to Biden, and said they looked forward to working together on areas of mutual interest.
Biden also told reporters he had discussed the Irish border issue with UK Prime Minister Boris Johnson and other leaders.
Biden, who has Irish heritage, said he was against a guarded border, arguing it must be kept open: "The idea of having the border north and south once again being closed, it's just not right."
Speaking to NBC, Biden said outreach from the White House had been "sincere", not "begrudging".
There were, he said, plans for him to meet the Covid task force in the White House about vaccine distribution and access.
Barack Obama's former vice-president said that his time in office would not be a "third Obama term" because "we face a totally different world than we faced in the Obama-Biden administration".
What are Republicans saying?
In a brief appearance in the White House press room on Tuesday, Trump praised the work of his administration, hailed the Dow Jones stock index for passing the 30,000 mark and left without taking questions.
While praising the armed forces later in the Rose Garden, he said: "And as I say, 'America First'. Shouldn't go away from that... 'America First'."
Arkansas Senator Tom Cotton said Biden had surrounded himself with "panda huggers" who would go soft on China.
Florida Senator Marco Rubio, who is on the committee that will vote on Blinken's nomination, tweeted: "Biden's cabinet picks went to Ivy League schools, have strong resumes, attend all the right conferences & will be polite & orderly caretakers of America's decline."