via Ace, The Washington Post casually mentions this in paragraph four of a story about the White House getting ready to get tough on critics…

When critics lashed out at President Obama for scheduling a speech to public school students this month, accusing him of wanting to indoctrinate children to his politics, his advisers quickly scrubbed his planned comments for potentially problematic wording. They then reached out to progressive Web sites such as the Huffington Post, liberal bloggers and Democratic pundits to make their case to a friendly audience.

Emphasis mine.

So there you go. He had a different message planned, but scrapped it after the critics called him on it in advance.