In September 2009, after a month that nearly saw legislative support for his domestic agenda collapse, President Barack Obama convened a joint session of Congress to focus the minds of wavering Democrats on the task at hand: reforming the nation’s health care system.

For nearly an hour, Obama defined the goals of his proposal, explained its importance and its function, and listed his criteria for signing legislation. (It was in this address, after Obama said his health reform plan would not subsidize illegal immigrants, that Republican Congressman Joe Wilson shouted “you lie” at the president, setting the tone for Republican opposition for the coming seven years.)

Legislative momentum is a nebulous concept. It is possible that the speech saved his legacy, or that the Affordable Care Act would’ve passed anyhow. But with his signature initiative on the line, Obama left nothing to chance.

The joint address President Donald Trump gave Tuesday night was a more traditional event. Every new president gives one, much like a state of the union address, but before a new president has had a chance to shape the union itself. It is unsurprising that Trump would be tempted to use his speech to re-champion his vision for the country and place himself above the parliamentary squabbling that powers Congress.

But if anything, at this extremely early date, Trump’s legislative agenda is more imperiled than Obama’s was in that September speech. It is conceivable that Republicans in Congress will find themselves unable to repeal Obamacare—the first domino in a procedural cascade that will leave the GOP with little or nothing to show for consolidating control of government.