Gallup 10/19: 52 Obama - 42 McCrud

After they've taken into account Powell's endorsement.

Obama will have a solid 10+ lead after it, and maybe even 15+ I think by the election. (Or maybe I'm just hopeful)

that Macs ceiling is 42%. I think he can call it a day.

and the Expanded (+7) and Traditional(+3) polls? I know the difference between the latter two, but what is the tracking measuring differently?

Expanded is what they believe turnout will be. Traditional is based on 4 years ago turnout, which I believe someone said was one of the largest Republican turnouts in history (I could be wrong). Pretty amazing--Obama leads in every single one.

Expanded is based on poll participants' response to the question about whether they intend to vote. That gives Obama a 7% lead.

Traditional is based on whether they voted in 2004. That gives Obama a 3% lead.

Registered is based on people who are just registered voters, which gives Obama a 10% lead.

Both of their likely voter models indicate that McCain supporters on average are more likely to turn out than Obama voters. I wonder if the combination of enthusiasm and GOTV will actually make for a surprise where Obama gets more then the registered voters margin.

They ask the voter these questions to screen their answers.

1. Are you registered to vote?
If they answer yes they will be included in the registered voters sample.

2. Do you plan on voting in the upcoming election?
If they answer yes they will also be included in the expanded likely voter sample.

3. Have you voted in past elections?
If they answer yes they will also be included in the tradition likely voter sample.

Now as I said this is a simplification, so these are not the exact questions, but its the basic idea. The registered voter screen will include all the newly registered voters, the expanded will include those expressing a high likelihood of voting, and the traditional screen will only include prior voters that have usually voted in the past and express a high likelihood of voting in this election.

He loses.

We win!