WASHINGTON — Donald Trump, the real estate mogul and reality television star who upended American politics and energized voters angry with Washington, was sworn in Friday as the 45th president of the United States, putting Republicans in control of the White House for the first time in eight years.

“It all begins today!” Trump tweeted at daybreak, before heading to a morning church service with his family as light rain fell. “THE MOVEMENT CONTINUES – THE WORK BEGINS!”

Ebullient Trump supporters flocked to the nation’s capital for the inaugural festivities, some wearing red hats emblazoned with his “Make America Great Again” campaign slogan. But in a sign of the deep divisions Trump sowed during his combative campaign, dozens of Democratic lawmakers were boycotting the swearing-in ceremony on Capitol Hill.

While Trump came to power bucking convention, he was wrapping himself in the traditional pomp and pageantry that accompany the peaceful transfer of power. From church, the president-in-waiting will head to the White House to meet President Barack Obama and first lady Michelle Obama for tea. The Trumps and the Obamas will travel together in the presidential limousine for the short trip to the Capitol for the noon swearing-in ceremony.

Trump supporters started lining up at security checkpoints before dawn to take their places in the quadrennial rite of democracy.

“I’m here for history,” said Kevin Puchalski, a 24-year-old construction worker who drove from Philadelphia. “This is the first president that I voted for that won.”  His big hope: Trump builds that promised wall on the U.S.-Mexican border. “Keep the illegals out,” he said. voted for that won.”  His big hope: Trump builds that promised wall on the U.S.-Mexican border. “Keep the illegals out,” he said.

Protesters, too, were out early, some trying to block inaugural visitors from passing through security checkpoints, some wearing orange jumpsuits with black hoods over their faces. Police in riot gear were out in force.

Eleanor Goldfield, who helped organize the Disrupt J20 protest, said demonstrators hope to show they will not be silent throughout Trump’s presidency. She called Trump supporters “misguided, misinformed or just plain dangerous.”

Trump aides said the president-elect had been personally invested in crafting his inaugural address, a relatively brief 20-minute speech that is expected to center on his vision for what it means to be an American. Spokesman Sean Spicer said the address would be “less of an agenda and more of a philosophical document.”

Trump has pledged to upend some of Obama’s major domestic and national security policies, including repealing his signature health care law and building a wall along the entire U.S.-Mexico border. But he’s offered few details of how he plans to accomplish his agenda, often sending contradictory signals.

The three days of inaugural festivities kicked off Thursday. Trump left his Trump-branded jet in New York and flew to Washington in a government plane, saluting an Air Force officer as he descended the steps with his wife, Melania. He and the incoming vice president, Mike Pence, solemnly laid a wreath at Arlington National Cemetery before joining supporters for an evening concert at the Lincoln Memorial.

“We’re going to unify our country,” Trump said at the close of the two-hour concert featuring country star Toby Keith, soul’s Sam Moore and The Piano Guys.

With rain a possibility, the National Park Service announced that it was easing its “no umbrella” policy for Friday, allowing collapsible umbrellas along the parade route and on the National Mall.

The nation’s soon-to-be president joked about the chance of a downpour. “That’s OK,” Trump told campaign donors at an event Thursday night, “because people will realize it’s my real hair.”

“Might be a mess, but they’re going to see that it’s my real hair,” he said.

Whatever the weather, Trump supporters were looking ahead to the day.

Chris Lehmann, 55, a maintenance supervisor from Belmar, New Jersey, said: “I’m so excited, I’m like, on top of the world.”

Eleanor Haven, 83, of Alexander City, Alabama, was attending the festivities with her son, Scott Haven. The pair said they had never been to a political event before attending a Trump “thank you” tour rally in Alabama after the election and were looking forward to Friday’s celebration.

“We’re excited for changes in the country,” Scott Haven said.

Celebrities were weighing in from all parts of the globe. Matthew McConaughey, in London to promote movies, stressed a need for acceptance, saying, “The votes came in, the peaceful transfer of power should happen today and we all need to embrace that.” James Taylor, a vocal Trump critic, emailed a video postcard from his vacation in French Polynesia, saying that on the last day of the Obama administration, “it feels like it’s raining all over the world.”

All of the living American presidents were attending the swearing in ceremony, except for 92-year-old George H.W. Bush, who was hospitalized this week with pneumonia. His wife, Barbara, was also admitted to the hospital after falling ill. Trump tweeted his well-wishes to the Bushes, saying he was “looking forward to a speedy recovery.”