Yesterday I posted two of Joe Biden’s new commercials, which present him as the only Democratic presidential candidate with a serious plan for getting U.S. troops out of Iraq without provoking a regional war in the Middle East or a worse Iraqi civil war.

Biden tried to hammer home this point at the Democratic debate on Sunday in Iowa, and that provoked a very revealing exchange between the candidates.

I’ve put most of the exchange in the jump. If you give it a read you’ll come away with a better sense of what the leading Democratic candidates would do about getting troops out of Iraq. You’ll also find out who’s in favor of partition, who’s worried about “overselling” how soon troops could reasonably come home, and who wants to dodge the question and downplay the divisions between Democrats on this issue.

First up was Bill Richardson, who talked about his "one-point plan" for Iraq (which, Richardson has said in the past, is simply to get all U.S. troops out by the end of this year, except those needed to guard the embassy). After that, one of the moderators turned to Biden and asked him what he thought of Richardson's plan. As transcribed by ABC News:

BIDEN: My reaction is that it's time to start to level with the American people. This administration hasn't been doing it for seven years. We should.

The fact of the matter is, there's much more at stake in our security in the region depending on how we leave Iraq.

If we leave Iraq and we leave it in chaos, there'll be regional war. The regional war will engulf us for a generation. It'll bring in the Shia, it'll bring in the Saudis, it'll bring in the Iranians, it'll bring in the Turks.

I laid out a plan a year ago with Leslie Gelb. It said that what we should do is separate the parties, give them breathing room in order to establish some stability.

I notice most of my colleagues are coming around to that plan these days. But the bottom line is it's going to one full year, if you argued tomorrow to get every single troop out.

And when you begin to take the troops out, what are you going to do with the 4,000 or 5,000 civilians that are left inside the Green Zone?

Noting that the Chairman of the Senate Foreign Relations Committee was saying one thing (that troops can't be out by the end of this year) while a former U.N. ambassador was saying another thing (that they can), the moderator turned to Clinton, saying, "Help a Democrat out... Who's right?"

CLINTON: Well, let me tell you what I would do, because I think that we need to do three things. We need to begin moving our troops out, and we have to do it carefully and responsibly. Joe is absolutely right.

Moving troops out cannot happen without careful planning, which is why I've been pushing the Pentagon to make sure they're actually planning because they've been resistant to doing so.

Secondly, we need much stronger pressure on the Iraqi government than this administration has been willing to bring.

CLINTON: And I would certainly condition any aid of any kind on their actually making the political decisions that they have been reluctant and unwilling to do so far. There is no military solution. Everybody agrees with that. And the political solutions seem to be out of the grasp of the Iraqis, because they're still jockeying for power...

This is going to be very dangerous and very difficult. A lot of people don't like to hear that.

But, if you look at how we would have to take our troops out, plus the equipment, which we would not want to leave, plus what we do with the people in the Green Zone, plus what we do with the Iraqis who sided with us -- thousands of them -- plus, what we do with the more than 100,000 American contractors who are there -- this is a massive,
complicated undertaking...

STEPHANOPOULOS: So does that mean that Governor Richardson just is wrong when he says that all troops, all troops, except for protection of the embassy, can be out by the end of the year?

CLINTON: Well, I think that based on the conversations I've had with military planners and outside experts, Joe is right, that this is going to take a while. People say you can move maybe a brigade to two brigades a month.

It is so important that we not oversell this. We've got to move them as quickly as possible, but you also have to move out the equipment. There has been no indication that the Turks are willing to let us move out. They wouldn't let us move in.

That means we go back down through the south. And if you remember, when we were supposedly on the road to liberation, we were attacked by Shiites back in March and April of 2003. So this is not going to be easy or safe. And we've got to be very careful about how we do it.

Next up, Edwards, who basically dodged the question, trying to blur the differences between the Democrats:

STEPHANOPOULOS: Senator Edwards, can all the troops be out, except for protection of the embassy, by December?

EDWARDS: I think it would be hard to do by December. I think we can responsibly and in a very orderly way bring our troops out over the next nine or 10 months.

But one thing I want to say, as I'm listening -- I know you're trying to create a fight up here, I understand that, but any...

STEPHANOPOULOS: I want to find out what you all think.

EDWARDS: ... any -- any Democratic president will end this war. That's what we know.

And secondly...

(APPLAUSE)

... the differences between us, whether it's Senator Clinton or Senator Dodd or Governor Richardson or Senator Biden, all of whom I have enormous respect for, the differences between all of us are very small compared to the differences between us and the Republican candidates.

And then it was Obama's turn. He also tried to blur differences, and used the opportunity to point out again that he hadn't supported the war in the first place.

STEPHANOPOULOS: Senator Obama, where do you come down on this question? How many troops are going to have to stay for how long?

OBAMA: I think Joe is right on the issue of how long this is going to take. This is not going to be a simple operation. I think Senator Clinton laid out some of the challenges that were out there. I agree with John Edwards that all of us on this stage I think would begin to bring this war to an end.

I think we also can all agree that it's going to be messy, that there are no good options.

OBAMA: There are only bad options and worse options, and we're going to have to exercise judgment in terms of how we execute this. But the thing I wish had happened was that all the people on this stage had asked these questions before they authorized us getting in.

And I make that point...

(APPLAUSE)

... because earlier on we were talking about the issue of experience. Nobody had more experience than Donald Rumsfeld and Dick Cheney and many of the people on this stage that authorized this war.

(APPLAUSE)

And it indicates how we get into trouble when we engage in the sort of conventional thinking that has become the habit in Washington. Now, that judgment is going to have to be exercised moving forward, and I actually think that Joe's point about partition might be the right one.

The only area I disagree with -- with Joe on that -- is that it is important for the Iraqis to arrive at the conclusion that partition makes sense, as opposed to it being imposed by the United States government.

OBAMA: Because I think if that happens, if the perception is that we are carving up the country as opposed to the parties arriving at a decision, then that could antagonize some of the factions and actually make the problem worse.

STEPHANOPOULOS: Senator Obama, you've invoked the idea of conventional thinking a few times here, yet when I listen to what you're saying about what you would do in Iraq, now it sounds very similar to what Senator Clinton would do.

Is there any difference between you and Senator Clinton on what you would do right now?

OBAMA: My sense is that what all of us need to do over the next 16, 18 months is focus on putting pressure on Republicans to stop giving George Bush a blank check, because if we have to wait for 16, 18 months, that's going to make the situation that much worse.

If we have not began a withdrawal by the time I'm sworn into office, then the next task is to call together the Joint Chief of Staff and to give them the mission, which is to begin an orderly, phased withdrawal, so that we can begin the diplomacy that Joe and Bill and others are talking about.

But look, as I said, there are no good options at this point.

OBAMA: This is the equivalent of George Bush drove the bus into the ditch, and there are only so many ways you can pull that bus out of the ditch. That doesn't mean you don't fire the driver, and it doesn't mean that you don't evaluate how we avoid getting in these same problems in the future.