President Donald Trump’s initial address to a joint session of Congress Tuesday night may be the most anticipated in memory. Not, as Trump would claim, because he’s so compelling. Rather it’s because, when it comes to substance, we don’t know who he is. For Presidents Barack Obama, George W. Bush and Ronald Reagan, a first February speech to Congress was a chance to add definition to well-articulated policy architecture. Trump, by contrast, has conveyed little sense of a governing structure, preferring to recycle the insults and cliches that defined his campaign.

On issues ranging from health care, taxes and the budget to China, NATO and foreign interventions, in five weeks he has created more confusion than clarity. Whether that reflects a lack of knowledge or lack of interest, Tuesday offers an opportunity for a reset.

In broad strokes — he’s not presenting a budget, so it’s reasonable to leave out the fine detail — he can spell out priorities and preferences. Is he willing to delay his announcement of a huge infrastructure project until next year, as many Republican congressional leaders wish? How will he slash spending without touching big entitlements like Social Security and Medicare, as he promised voters in the fall?

Republicans are tied in knots over how to fulfill their pledge to repeal and replace Obamacare. Trump has vowed to enact universal coverage that’s better and cheaper. He should explain how to perform that impossible balancing act.

On taxes, it would be useful to hear what Trump thinks of the big new “border-adjusted” sales tax favored by House Ways and Means Committee Chairman Kevin Brady and Speaker Paul Ryan. A variation of a European-style, value-added levy that favors exporters over importers, it’s on political life support. Trump could either help revive it, or kill it by not mentioning it.

It’s probably asking too much to call on this president to quit pretending that he can fulfill his campaign promises cost-free, and to start explaining how he wants to pay for them. That includes the big increase in military spending he’s sure to embrace; will he lay out a strategy to justify his Pentagon wish list?

Republicans used to criticize Obama for what they called a global “apology tour,” wrongly claiming that his speeches in historical hot spots like the Middle East and Vietnam amounted to blaming the U.S. for the world’s contemporary problems. Over the last several weeks, however, Trump Cabinet members really have been on a “he-didn’t-mean-it” tour, insisting that allies can safely ignore Trump’s anti-Muslim narrative or stated disdain for the North American Treaty Organization and the U.S.-provided security umbrella in Asia.

Another sign of confusion that Trump could address Tuesday night came when the president denied Secretary of State Rex Tillerson his choice of veteran diplomat Elliott Abrams as deputy secretary of state — the appointment was nixed just before it was to be announced when Trump was told about derogatory statements Abrams made about him during the campaign. Beyond the management issues raised by undercutting a secretary of state, the incident raised policy questions. Abrams is a prominent neoconservative, a supporter of the Iraq war and robust American interventionism. This was exactly what Trump campaigned against, even lying about his early support for the Iraq War. Now there’s chatter about creating security “safe zones” in war-torn Syria backed by an infusion of U.S. forces.

Trump, not a big reader, would do well to glance at the initial congressional speeches of his two immediate predecessors. Both laid out clear policy priorities: Obama for investments in clean energy and education and universal health-care coverage, Bush for tax cuts and selective education initiatives. Both addresses indicated that national security would be secondary.

The White House has put out the word that Tuesday’s speech will be more upbeat in tone than Trump’s darkly hued inaugural address. That would be welcome. Maybe he’ll even stop fudging the truth. Contrary to his claims, he has not accomplished more than any president at a comparable stage; Obama had real legislative achievements a month into his presidency and the Reagan and Bush agendas were further along.

Here’s another forlorn hope for Tuesday night: Might this self-absorbed, humorless man show a flash or two of a lighter side?

Albert Hunt is a Bloomberg View columnist.

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