When the president addresses Congress on Wednesday night, he will be making his 28th speech on the subject — and that doesn't count the innumerable times he has discussed the matter in less formal ways.

None of this talking has halted the downward slide in public approval of his health reform ideas and of his performance on the issue. There is little evidence that Obama will make a major adjustment in his proposals, not even to abandon the highly controversial idea of a new government-sponsored health insurance program, the so-called public option. Nor is there any sign he might offer something new that might appeal to Republicans, such as lawsuit reform to curb malpractice awards and the huge insurance premiums that go with them.

That leaves the president with the task of convincing members of Congress to go along with a set of ideas that very nearly got some of them tarred and feathered at stormy town hall meetings back home.

They don't call the White House the bully pulpit for nothing, but there is a long history that suggests that the presidential speech is a depreciating asset: The more it's used, the less effective it becomes.

So far, President Obama's much-admired speaking style seems to have been effective at selling him personally, but much less so at promoting his ideas.

Absent any new ideas Wednesday, he is facing quite a challenge.

Brit Hume is the senior political analyst for FOX News Channel.