The marathon of the presidential campaign ends at the finish line with Donald Trump the victor setting off on a sprint toward Inauguration Day.

Now begins the work of passing power from President Barack Obama to President-elect Trump.

The transition begins in offices assigned to Trump in downtown Washington, where a team he assembles will fan out to 60 federal agencies and departments to begin getting schooled on procedures and policies.

Meanwhile, Trump must embark on a hiring spree.

He'll have to appoint a Cabinet and fast, vetting potential nominees to avoid choices who turn out to have skeletons lurking in their past.

The new president must appoint more than 4,100 senior level positions across the government.

"I am absolutely convinced that you can make some mistakes in those 73 days between election and the inaugural that will haunt you for the rest of your presidency," said Harrison Wellford who has advised four presidents during transitions.

Wellford said Trump would be wise to consult people who've been through the process.

"It's difficult for anybody," he said. "But for people without much experience it can be extremely surprising how hard it all is, just all this stuff coming at you."