Tonight’s address to the nation from the White House on the future in Afghanistan won’t be terribly interesting. By now we know the outlines: President Obama will announce a drawdown of “second surge” troops, about 33,000 in all, by the end of 2012. So there will still be 66,000 troops or so in Afghanistan by the end of Obama’s first term, around twice as much as there were in the beginning of the term. Whether 5,000 leave now or 10,000 leave now or whatever, that’s the bottom line.

I recognize that the troop levels are not quite as important as the underlying strategy, particularly an exit strategy rooted in peace talks with the Taliban. But while the President will announce some minor progress on that front, I don’t think there will be much of value there either.

So what will be interesting is the public response from members of Congress. Carl Levin, for example, the chair of the Senate Armed Services Committee, said yesterday that a minimum of 15,000 troop withdrawals would satisfy him, nothing less.

“In my judgment, a minimum of 15,000 reduction in troops would be needed for this to be a significant reduction, and since the president has committed himself a few months ago to a significant reduction, I think that’s what will happen,” Levin told reporters on Capitol Hill on Tuesday.

When asked how he came up with that number, Levin replied, “It’s based on what would it take to let the Afghans know the significance of the importance of shifting the responsibility — the principal responsibility to them for the security of their own country.”

So what does Levin say tonight when that number comes up short? The above-linked article has Jeff Merkley, Silvestre Reyes and John Garamendi also saying that the numbers we’re hearing won’t be good enough. In this sense, these lawmakers are siding with the public, who would prefer to just get the heck out of Afghanistan entirely. What does that trigger? How will Congress react?

I mean, here’s noted hippie Joe Manchin:

Sen. Joe Manchin (D-WV) said he could only base his opinions on what he saw on a recent Afghanistan trip.

“I did not see improvement. I saw deterioration,” Manchin said Tuesday. “I saw corrupt leadership…and I can only speak to a feeling of common sense…if 10 years is not enough [to establish stability], how long are we going to be staying there and spending billions when we can’t repair the bridges or fix the roads in our states.”

The cost of war is definitely emerging as a factor here.

Members are waiting for the announcement to comment fully. But I doubt it will be favorable. The question is how unfavorable, and what actions get taken as a result.

UPDATE: There’s actually another letter going out today, from the House side, calling for a “sizable and significant drawdown” of troops. It’s being led out of John Garamendi’s office. At least 57 House members have signed so far.