With just over three weeks to go until President-elect Donald Trump is sworn in, he has selected Stephen Miller, his senior White House adviser for policy, to write the inauguration speech, Politico reports.

Miller, who wrote most of Trump's major prepared speeches this year, including the address at the Republican National Convention, has reportedly been putting together an initial draft of the inauguration speech, even though he has also been busy drafting remarks for Trump's "thank you" tour.

The major themes of the address are expected to be some of the main issues Trump spoke of during the campaign, such as border security, the economy, military preparedness, infrastructure, and the nation's education system.

Trump has declared he wants to immediately tackle several different issues in his first 100 days, and the inauguration speech is the first major address with an international audience to lay out a road map for doing so.

Peter Wehner, a Bush speechwriter who has been critical of Trump, told Politico that the address should not have the same tone as his campaign speeches.

"A campaign message is taking place in the context of a conflict and you have an opponent and you're trying to defeat that person, [while] an inaugural speech is the exact opposite of that," Wehner told Politico.

"That's the one moment where you really need to go in the opposite direction and try to bring the country together."

The Trump team has indicated that it might follow that philosophy, as they speak of unifying concepts to fix the nation's problems, rather than his theme of "I alone can fix it" that was so prominent in the convention address and during the campaign.

However, Trump is also reportedly interested in crafting Inauguration Day with a populist outsider theme to emphasize that he is "the people's president." For example, by possibly wading into the crowd after his speech or joining the parade, rather than going directly to the traditional congressional luncheon following the swearing-in.

Miller was instrumental in formulating Trump's "America First" agenda during the campaign, The Daily Caller reports.

That included helping develop Trump's plan to suspending immigration from nations dealing with high rates of terrorism and his vision for defeating Islamic extremism.

Miller previously worked for GOP Sen. Jeff Sessions of Alabama, who Trump has tapped for attorney general.