A note to our readers and viewers: The Democratic and Republican polling firms that conduct the NBC/WSJ poll have announced that the survey is expanding the number of cell phone-only respondents.
In February, the percentage of cell phone-only respondents was increased to 25% of the survey (so 250 out of 1,000). Now it will be 30% (300 out of 1,000).
This expansion comes as our pollsters believe that about one third of the 2012 electorate will consist of voters who use only cell phones and don't have landline phones.
Here is a memo from our NBC/WSJ pollsters.