 -- The White House is promising an “optimistic vision” and a “bold agenda” from President Trump when he speaks in front of a joint session of Congress Tuesday night. This president, of course, knows prime time. But this will be a speech unlike any he has given before.

Here is a glimpse at some of the storylines to watch Tuesday night:

Meat on Bones

Tuesday’s address begins a new phase of the Trump presidency -– a part where congressional buy-in is no longer optional. Members of Congress are growing desperate for answers from the White House on key policy priorities, starting with Obamacare, immigration, and the border wall as well as tax reform, infrastructure and trade. Trump has thus far left the legislative heavy lifting to congressional leaders who have been alternately liberated and frustrated by the lack of White House guidance. That will need to change starting Tuesday night, where Trump’s first speech to an assembled Congress will force him to put legislative meat on the rhetorical bones that haven’t grown much since the campaign.

Replacement Plan

The most immediate -– and perhaps most consequential -– policy area where the president needs to get specific is on healthcare. “Repeal and replace” carries less meaning than ever as a plan now that we’re five weeks into the GOP’s full control of Washington. Trump has been decidedly vague, and sometimes contradictory, in his pronouncements about wanting to expand health care access, bring down costs and repair insurance markets. “Nobody knew that healthcare could be so complicated,” the president declared on Monday, leaving aside the fact that everybody has always sort of known that. The conservative base is getting restless. And millions of Americans who rely on Obamacare or its market reforms are getting rightfully anxious.

Opposition Parties

Between the inauguration, presidential speeches, White House and Mar-a-Lago meetings, and even a post-election campaign speech, President Trump has not yet faced a crowd that wasn’t either hand- or self-selected as generally supportive since he took office. (That is, unless you count his press conferences, where the president has faced down those whom he considers the “opposition party.”) Assuming boycotts don’t thin their ranks, almost half the room in the House chamber will be actual members of the opposition party -– the Democrats, who are feeling intense pressure from their base not to cooperate with anything the president proposes. Will any of them try something designed to get under Trump’s skin? Back to the other opposition party, will Trump keep up his anti-media broadsides in front of Congress -– and a national TV audience?

Just Facts

President Trump has stretched more truths -– and perpetrated more outright falsehoods -– than your typical new president. Now comes a new forum: A speech to a joint session of Congress, where even small factual errors have had the potential to launch congressional investigations in the past. With little visibility surrounding the White House’s fact-checking operation, it remains unclear whether the president will engage in the exaggerations and mistruths that have littered so many of his speeches, to say nothing of “alternative facts.” Will he claim –- without evidence -– to have rightfully won the popular vote because of widespread fraud? Will his statistics on jobs, immigration, trade, and military might stand up to scrutiny? Can a speech go by where he doesn’t mention -– or overstate –- his Electoral College margin?

Base Moves

The Trump White House has gone out of its way to keep conservatives happy, with a Supreme Court selection and a high-profile speech at the Conservative Political Action Conference just two data points in a strategy of base maintenance. Expect the president to trumpet early promises kept, and press for a quick confirmation vote for Judge Neil Gorsuch. But how conservative will the president want to come across in this setting? His base remains behind him, but the broader public appears somewhere between skeptical and hostile about his leadership. Any explicit outreach to Democrats will be closely watched –- yet could prompt quick blowback.

Russia's Shadows

One very big campaign story churns on, and is threatening to overshadow all in the early months of a Trump presidency. Calls for an independent investigation into the Trump camp’s ties with Russia, coupled with the president’s kind words about Vladimir Putin, leave Russia as the dominant foreign-policy storyline coming in to Tuesday. Trump appears unlikely to mention the swirling controversy, but it’s all that Democrats -– and now even a few Republicans –- want to talk about when it comes to foreign policy. Any national security pronouncements that come from the president will be viewed through the lens of Russia. And body language between the president and congressional watchdogs on the House floor will be freeze-framed and scrutinized.

Democratic Response

The out-of-power party’s formal television response is typically a chance to highlight a rising star. Not so this year, with the selection of 72-year-old former Kentucky Gov. Steve Beshear to be the Democrats’ most prominent spokesperson for this one night. Beshear is a moderate from a deep-red state that happens to also be home to Senate Majority Leader Mitch McConnell. More relevantly for his likely message, he presided over one of the biggest success stories of Obamacare, with Kentucky’s health care exchange and Medicaid expansion. The Spanish-language response will come from Astrid Silva, an immigration activist and so-called DREAMer who benefited from the Obama administration’s leniency toward undocumented immigrants who were brought to the United States as children. The choices of Beshear and Silva suggest that Democrats want to engage Trump on policy more than personality.

Trump Show

Nothing has been quite what it’s been in the past under President Trump. Why should the normally staid pageantry of a joint-session speech be any different? There will be a teleprompter, but no guarantee that he’ll stick to it. The world will be watching for any distinctly Trump flourishes, and whether anything he says will bring Democrats to their feet –- or keep Republicans off of theirs. Then there are questions of family, including how many Trump children will be in attendance. It’s also a high-profile night for first lady Melania Trump, who will be making one of her first official appearances in hosting guests in her box in the House chamber.