WASHINGTON (AP) — President-elect Joe Biden is set to formally introduce his national security team to the nation, building out a team of Obama administration alumni that signals his shift away from the Trump administration's "America First" policies and a return to U.S. engagement on the global stage.

The picks for national security and foreign-policy posts include former Secretary of State John Kerry to take the lead on combating climate change. Kerry and several other people set to join the upcoming administration will be discussed by Biden and Vice President-elect Kamala Harris during a Tuesday afternoon event.

Outside the realm of national security and foreign policy, Biden is expected to choose Janet Yellen as the first woman to become treasury secretary. She was nominated by President Barack Obama to lead the Federal Reserve, the first woman in that position, and served from 2014 to 2018.

Biden's emerging Cabinet marks a return to a more traditional approach to governing, relying on veteran policymakers with deep expertise and strong relationships in Washington and global capitals. And with a roster that includes multiple women and people of color — some of whom are breaking historic barriers in their posts — Biden is fulfilling his campaign promise to lead a team that reflects the diversity of America.

The incoming president will nominate longtime adviser Antony Blinken to be secretary of state; lawyer Alejandro Mayorkas to be homeland security secretary; Linda Thomas-Greenfield to be U.S. ambassador to the United Nations; and Jake Sullivan as national security adviser. Avril Haines, a former deputy director of the CIA, will be nominated as director of national intelligence, the first woman to hold that post.

Thomas-Greenfield is Black, and Mayorkas is Cuban American.

Those being introduced on Tuesday "are experienced, crisis-tested leaders who are ready to hit the ground running on day one," the transition said in a statement. "These officials will start working immediately to rebuild our institutions, renew and reimagine American leadership to keep Americans safe at home and abroad, and address the defining challenges of our time — from infectious disease, to terrorism, nuclear proliferation, cyber threats, and climate change."

In the weeks ahead, Biden could also name Michèle Flournoy as the first woman to lead the Defense Department. Pete Buttigieg, the former Indiana mayor and onetime presidential candidate, has also been mentioned as a contender for a Cabinet agency.

In making the choices public on Monday, Biden moved forward with plans to fill out his administration even as President Donald Trump refused to concede defeat in the Nov. 3 election, has pursued baseless legal challenges in several key states and worked to stymie the transition process.

Trump said later Monday that he was directing his team to cooperate on the transition but vowed to keep up the fight. His comment came after the General Services Administration ascertained that Biden was the apparent winner of the election, clearing the way for the start of the transition from Trump's administration and allowing Biden to coordinate with federal agencies on plans for taking over on Jan. 20.

Biden's nominations were generally met with silence on Capitol Hill, where the Senate's balance of power hinges on two runoff races that will be decided in January.

The best known of the bunch is Kerry, who made climate change one of his top priorities while serving as Obama's secretary of state, during which he also negotiated the Iran nuclear deal and the Paris climate accord. Trump withdrew from both agreements, which he said represented a failure of American diplomacy in a direct shot at Kerry, whom he called the worst secretary of state in U.S. history.

"America will soon have a government that treats the climate crisis as the urgent national security threat it is," Kerry said. "I'm proud to partner with the president-elect, our allies, and the young leaders of the climate movement to take on this crisis as the president's climate envoy."

Blinken, 58, served as deputy secretary of state and deputy national security adviser during the Obama administration. He recently participated in a national security briefing with Biden and Vice President-elect Kamala Harris and weighed in publicly just last week on notable foreign policy issues in Egypt and Ethiopia.

Blinken served on the National Security Council during the Clinton administration before becoming staff director for the Senate Foreign Relations Committee when Biden was chair of the panel. In the early years of the Obama administration, Blinken returned to the NSC and was Biden's national security adviser when Biden was vice president, then moved to the State Department to serve as deputy to Kerry.

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Associated Press writers Michael Balsamo in Washington, Bill Barrow in Atlanta and Alexandra Jaffe in Wilmington, Delaware, contributed to this report.