WASHINGTON — The true test now begins for Donald Trump.

The Republican president-elect paid little attention to transition planning leading up to his stunning victory. With 72 days before he takes control of the executive branch, Trump and his senior team on Wednesday immediately began the herculean task of picking a Cabinet and tapping hundreds of appointees to senior roles in key departments — State, Defense, Homeland Security, Commerce and Treasury among them — many requiring multiple security reviews or Senate confirmation.

“They have a long way to go,” said Max Stier, president and CEO of the Partnership for Public Service, an outside group that was working with both campaigns on transition planning since the summer. “It’s imperative to have the right people brought in fast and they’re prepared.”

Stier described the transition as “a point of maximum vulnerability” for the nation.

As president-elect, Trump is entitled to get the same daily intelligence briefing as President Barack Obama — one that includes information on U.S. covert operations, information gleaned about world leaders and other data gathered by America’s 17 intelligence agencies.

Trump’s team huddled privately to begin a more focused period of transition planning. The group included the transition chairman, New Jersey Gov. Chris Christie, Republican National Committee Chairman Reince Priebus, Alabama Sen. Jeff Sessions, Vice President-elect Mike Pence and daughter Ivanka Trump’s husband, Jared Kushner, among others.

The team is putting a premium on quickly filling key national security posts, according to people familiar with the conversations but not authorized to discuss them publicly.

“We had a great meeting and I thought it was valuable. And lots of work has been done,” said Sessions, a top Trump adviser. “So it’s the beginning, really a solid beginning. First phase of the beginning.”

Bill Hagerty, Trump’s director of presidential appointments, declined to detail a timeline for Trump’s first personnel moves. A chief of staff is traditionally appointed in the initial weeks after an election.

“It’s something that’s got to be pretty close held until the president-elect is ready to begin to announce appointments,” he said.

A small transition team has been meeting since early August to discuss legislative priorities and plans for taking over agencies. While Christie provided Trump with weekly updates, until now, the campaign and transition operations functioned as relatively distinct entities and in different cities — Trump’s campaign in New York and the transition team in Washington.

An organizational chart for the transition team obtained by The Associated Press confirms that some familiar names are playing senior roles in shaping a Trump administration.

National security planning was being led by former Michigan Rep. Mike Rogers. Joseph “Keith” Kellogg, a retired Army lieutenant general, was heading defense planning.