Donald Trump’s inaugural address will be relatively brief, and he’s going to revel at the sight of crowds carpeting the Mall as he speaks to the largest rally of his political career.

But what the 45th president will say to enlarge his message of “America first,” and the impact his words may have on his governance, remain unpredictable. Trump’s speeches are known for being improvisational more than set pieces, and memorable for putdowns more than poetry.

And Trump-bashing protesters in Washington could draw the new president into counterpunching.

But the grandeur and importance of addressing the nation as president has challenged the New York businessman to aim for vision and national aspirations rather than a political laundry list. “Very personal and sincere” was one description offered hours before Trump and his family flew to Washington from New York.

Speaking off-the-cuff in front of the Lincoln Memorial Thursday evening following a concert and fireworks show, Trump thanked those who voted for him and the thousands of visitors gathered in the nation’s capital. “There’s never been a movement like this … anywhere in the world,” Trump said. “And we’re going to unify our country. … We’re going to make our country great for all of our people.”

After saying Trump’s speech would focus more on vision and philosophy and less on specific policies, his spokesman noted that “he’ll talk about infrastructure and education, [and] our manufacturing base.” The repeal and replacement of Obamacare did not take center stage when the president-elect’s team previewed working drafts.

Trump’s top priorities remain immigration, job creation, manufacturing, and tax reform, incoming White House Press Secretary Sean Spicer told reporters Thursday. Within each of those politically fraught policies are kernels of bipartisan agreement. How Trump approaches enough Senate Democrats to support his legislative priorities will help define his approach to governance. Does he seek compromise to find bipartisan support? Or does he want to exploit anxiety about red-state contests next year to scare some moderate Democrats into collaborating with the White House?

Spicer said Trump will speak to Americans about the “proper role of government [and] the role of citizens,” which sounds a lot like what President Obama says he’ll focus on during his post-presidency.

Whether the Trump speech delivers a unifying message will be “in the eye of the beholder,” his spokesman said. Indeed, whether a 20-minute speech can possibly begin to heal raw political wounds is likely a tall order.

The address on Friday will be followed next week by a blizzard of Trump executive actions with which the new president says he will begin to erase Obama’s policies. After celebrating his swearing-in with family and friends, Trump’s first presidential steps may not look like…