Media playback is unsupported on your device Media caption Donald Trump said his inauguration day would be known as the day "the people became the rulers of this nation again"

If Donald Trump's speech at the Republican National Convention was billed as "midnight in America" - a pessimistic view of the current conditions in the US - then his message on inauguration day was that it's always darkest before the dawn. The nation was in peril, but America was about to be great again.

In an address that was tonally consistent with Candidate Trump's campaign rhetoric, the president railed against a Washington elite that flourished while the American people suffered.

"While they celebrated in the nation's capital, there was little to celebrate for struggling families all across our land," he said

He described a nation blighted with rusted-out factories, families "trapped in poverty", a public education system that deprived "young and beautiful" children of all knowledge and cities wracked by violent crime.

"This American carnage stops right here and stops right now," he said.

Early reports were that Mr Trump would offer a non-ideological appeal for national unity - and there were motions in that direction at times toward the end of his speech. This address, however, was very much aimed at his supporters - uniting the people with pitchforks against an out-of-touch establishment.

It was a call to arms for the disaffected Americans who fuelled the improbable rise of the New York real-estate mogul and reality television star to the White House.

He told them they would never again be forgotten or ignored. "Your voice, your hopes and your dreams will define our American destiny," he said.

This was not a message to the American people as a whole - many of whom likely feel the past resident of the White House, Barack Obama, reflected their beliefs and their diversity.

This was a speech for the angry, the frustrated, the American voters who turned out in places like Pennsylvania, Michigan, Florida and Ohio to shake their fist at the status quo and take a chance on a man who was unlike any presidential politician who came before him.

It should also serve as a wake-up call to American allies, as Mr Trump insisted that the US will put its own interests first both economically and militarily.

"We will follow two simple rules," he said. "Buy American and hire American."

Media playback is unsupported on your device Media caption Donald Trump: 'America first, America first'

For Mr Trump, giving this speech - and it clearly was a speech from his heart, if not directly from his pen - was the easy part. Making the promises to put America first, give power back to the people, bring jobs back, eradicate "radical Islamic terrorism" and rebuild US infrastructure isn't hard.

The challenge now will be to live up to his rhetoric as a different kind of president - and bring the rest of the nation along with him on the journey.

Congressional Republicans will advance their own priorities and follow their own path - one worn from years of tradition and ideology. What will Mr Trump do when their views diverge? Will an angry tweet or two suffice?

Democrats will dig into the trenches and plot how to undermine Mr Trump at every turn, counting the days until 2020.

American voters - at least ones in enough states to form an electoral college majority - have put their faith in Mr Trump. His presidency will be a remarkable experiment for American democracy, as it's clear after this speech that Mr Trump intends to govern as he campaigned.

The new president has set the stage. Now, as he said on the steps of the Capitol, it is the hour of action.

He has four years to make his supporters proud and prove all the doubters wrong.

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As Donald Trump prepares to take the oath of office, he faces public approval ratings for a newly elected president without precedent in modern US political history. The five most recent polls from major news networks have his positive ratings at 32%, 37%, 40%, 40% and 44%.

These early, heady early days of a president's administration are supposed to be his "honeymoon" with voters and political foes alike. It's the time when he's at the zenith of his power and most likely to be able to marshal bipartisan support for advancing his agenda with an eye toward making lasting changes.

Instead, the partisan divisions in the US seem sharper than ever - and the public tends to agree.

Part of this can be attributed to Mr Trump's narrow victory in the Electoral College and his nearly three million vote deficit to Hillary Clinton in the popular vote. Although the system worked the way it was designed, many Democrats feel cheated.

Then there are the continued allegations of Russian meddling in the presidential election and recent reports that there is an ongoing federal investigation into ties between former Trump advisors and Russian officials.

Exacerbating all this has been Mr Trump's behaviour in the days since his election. He continues to act like a candidate on the campaign trail, lambasting his opponents - including members of the intelligence community - roasting the media and answering every perceived slight and criticism with a broadside of his own. If he refuses to tone down his attacks, his adversaries will remain in their political trenches.

According to early reports, Mr Trump's inaugural address will chart a different course - decrying "ideological thinking" and emphasising unity.

If this turns out to be the case, the question becomes whether this marks the beginning of a new direction or a temporary blip.

What first for Trump?

Columnist Mark Shield has observed that when choosing a new president, American voters often appear drawn toward candidates who have attributes their predecessor in the Oval Office seemingly lacked.

Machiavellian Richard Nixon was replaced by do-gooder Jimmy Carter. Bill Clinton's unchecked appetites gave way to teetotaller George W Bush, whose perceived lack of eloquence stood in sharp contrast to next-in-line Barack Obama's erudition.

Now Mr Obama, criticised even by some supporters as being overly professorial and detached, is handing over the reins of power to a man known for blunt bombast and raw emotion. It's a dramatic swing of presidential temperament that will be matched by the seismic political changes that loom over the coming days.

For the past two years, Mr Obama and the Democrats in the executive branch have served as a check on Republicans in Congress.

With threat of a presidential veto and the broad powers federal agencies possess, they've managed to keep the Obamacare health insurance system intact, adjust immigration law enforcement, impose new environmental regulations to address climate change and maintain the closer oversight of the financial sector set out in banking reform laws passed in 2009.

Those days are over.

For the first time in 10 years, the Republicans will have unified control over the federal government. They have the opportunity to advance their agenda - and roll back Mr Obama's legacy - on a wide variety of fronts.

The biggest challenge facing Mr Trump and his party on this rainy January Inauguration Day is where exactly to start.