When a president schedules an address to a joint session of the Congress, he essentially says: “OK, folks, this time it’s for real.”

The speech to the assembled members of the House and Senate, with all its pomp and circumstance, is a much bigger deal than a televised press conference or even one of those, seated-behind-the-desk, eyes-on-the-camera statements that presidents usually deliver after having ordered bombs dropped on some distant land or when they must apologize for an impeachable offense that might yet be talked around.

So Barack Obama has set himself a tall task this Wednesday night.

He must grab hold of a drifting debate about healthcare reform and impose not just clarity but a sense of purpose and direction.

Prior to the speech, the president more or less acknowledged that he had blown the roll-out of the reform initiative.

Appearing on ABC-TV’s “Good Morning America,” the president admitted that he “probably left too much ambiguity out there, which allowed, then, opponents of reform to come in and to fill up the air waves with a lot of nonsense — everything from this ridiculous idea that we were setting up death panels to false notions that this was designed to provide health insurance to illegal immigrants.”

Aside from the word “probably,” that’s an accurate assessment of the fiasco.

Obama also seems to recognize that his first task is to explain to angry Americans and a confused Congress what it is that he wants.

“I think what the country is going to know is exactly what I think will solve our healthcare crisis, they will have a lot of clarity about what I think is the best to move forward,” Obama said Wednesday morning. “So the intent of the speech is to A, make sure that the American people know exactly what it is we are proposing, B, to make sure that Democrats and Republicans understand that I am open to new ideas, that not being rigid and ideological, but we do intend to get something done this year.”

The fact that “B” sort of contradicts, or at least undermines, “A” is not a hopeful sign.

Of course Obama must address the “death panel” extremes to which opponents of reform have pushed the debate.

As the president says, he has a responsibility to “dispel some of the myths and frankly silliness […] out there.”

But if the president is serious about “get[ting] something done this year,” his task involves a lot more than dispelling myths.

To live up to expectations, a joint address to Congress must be bold in its ambitions and precise in its definitions.

As such, the president needs to be careful about devoting too much time to the empty task of talking up his flexibility and his bipartisan tendencies.

Americans are painfully aware that this president is “open to new ideas.”

What they need is for Obama to “make sure that the American people know exactly what it is we are proposing.”