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J. Scott Applewhite, Associated Press
President Donald Trump is joined by the Congressional leadership and his family as he formally signs his cabinet nominations into law, in the President's Room of the Senate, at the Capitol in Washington, Friday, Jan. 20, 2017. From left are Senate Minority Leader Chuck Schumer, D-N.Y., Sen. Roy Blunt, R-Mo., Donald Trump Jr., Vice President Mike Pence, Jared Kushner, Karen Pence, Ivanka Trump, Barron Trump, Melania Trump, Speaker of the House Paul Ryan, R-Wis., Majority Leader Kevin McCarthy, D-Calif., House Minority Leader Nancy Pelosi, D-Calif.

WASHINGTON — President Donald Trump on Friday quickly claimed the mantle of the White House, signing legislation allowing retired Gen. James Mattis to serve as his defense secretary, as well as the nomination papers for his Cabinet choices.

Less than an hour after wrapping up his inaugural address, Trump sat in an ornate room steps from the Senate floor and signed a series of papers formally launching his administration. Flanked by Vice President Mike Pence and congressional leaders, he praised each of his nominees as he signed the papers and handed out the pens he was using, exchanges that allowed him to banter with his new congressional rivals, including Senate Democratic leader Chuck Schumer of New York and House Democratic leader Nancy Pelosi of California.

Trump also signed a proclamation declaring a national day of patriotism, according to a tweet from White House spokesman Sean Spicer.

The bill passed by Congress last week grants Mattis a one-time exception from federal law barring former U.S. service members who have been out of uniform for less than seven years from holding the top Pentagon job. The restriction is meant to preserve civilian control of the military. Mattis, 66, retired from the Marine Corps in 2013.

The signing ceremony captured Trump's first acts as president. The president distributed pens to top congressional leaders, handing the pen he used to formally nominate Elaine Chao, his choice for transportation secretary, to Senate Majority Leader Mitch McConnell, her husband.

When Pelosi jokingly objected to a pen used to nominate Rep. Tom Price of Georgia to lead the Department of Health and Human Services, House Speaker Paul Ryan interjected, "I'll take it."

While Trump participated in the ritual of the day, there were signs his new government was up and running. Federal websites and agencies immediately began reflecting the transfer of power, and WhiteHouse.gov was revamped to reflect Trump's policy priorities.

Gone was a page dedicated to outlining the president's policies on LGBT rights. Trump's site appears to make no reference to the issue.

And in place of a page promoting the Obama administration's Climate Action Plan was a page detailing Trump's "America First Energy Plan," which stresses Trump's commitment to "eliminating harmful and unnecessary policies such as the Climate Action Plan."

But the Trump team kept a section of the White House site that let voters petition the White House. Two new petitions were posted Friday: one calling on him to release his tax returns and verify that he is not receiving payments from foreign government, while the other asks him to divest of his holdings or put them in a blind trust.

Shortly after Trump became president, the Department of Housing and Urban Development suspended the Obama administration's planned reduction of mortgage insurance premium rates, a move that had been intended to make home ownership more affordable. Trump's choice to run HUD, Ben Carson, said at Senate hearings that he wants to examine the reductions.

Although Trump campaigned on promises to get to work immediately, Trump officials have said they expected Monday as the first big workday of the new administration, his effective Day One.

As a candidate, Trump assembled an 18-point plan of actions for his first day in office. But has backed off some of his promised speed, downplaying the importance of a rapid-fire approach to complex issues that may involve negotiations with Congress or foreign leaders. On others issues, he has affirmed the plan, indicating significant policy announcements may be teed up in the first hours and days of the Trump administration.

"The glacial pace and the excuse of divided government in Washington, those days are gone," said White House counselor Kellyanne Conway, who served as Trump's final campaign manager. "That really will be swept into the bin of recent history."

Spicer said Thursday that two executive orders on trade would be coming soon. On his Day One list, Trump said he would formally declare the United States' intention to withdraw from the 12-nation Trans-Pacific Partnership trade deal, which he vigorously opposed during his campaign as detrimental to U.S. businesses and workers. He also promised to declare his intention to renegotiate the two-decades-old Clinton era North American Free Trade Agreement or withdraw from the deal.

During the campaign, Trump promised to propose on his first day a constitutional amendment to impose term limits on members of Congress. He vowed to impose a hiring freeze for federal workers, and begin to remove immigrants who are criminals and living in the country unlawfully.

He also said he would "cancel every unconstitutional executive action, memorandum and order issued by President Obama."

Given Trump's opposition to Obama's immigration actions, that could mean cancellation of the Deferred Action for Childhood Arrivals program, or DACA, which has protected about 750,000 young immigrants from deportation. The program also offered those immigrants work permits.

If he terminates the program, Trump could choose to immediately cancel the deportation protection and revoke the work permits, or he could opt to block new enrollment and allow those already approved to keep their work permits until they expire.

Trump also faces an early choice of naming a Supreme Court justice to fill the vacancy left by the late Justice Antonin Scalia. Trump has said he will announce a nominee in about two weeks.

Other issues poised to receive early action include energy, where Trump is likely to undo regulations on oil drilling and coal, and cybersecurity, where he has already said he will ask for a report on the strength of the nation's cyber defenses within 90 days of taking office.

Associated Press writer Alicia A. Caldwell contributed to this report.

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