Oregon's vote-by-mail system may make polling a little more tricky close to election day. After all, a substantial portion of the electorate have already cast their ballots, while there are many who wait until just before the election to vote.
On this front, one interesting finding stands out when it comes to the surveys out of Oregon over the past week or so. According to polls from Survey USA and American Research Group, Obama has a significant lead in Oregon among those who intend to vote, but he is in a dead heat with Clinton among those who say they have already voted.
In the Survey USA poll (conducted 5/9-11), 43% reported that they had already mailed in their ballots and Obama's lead in this group was just 49-48% (well within the margin of error). On the other hand, among those who intended to vote but had not yet done so, Obama a 58-38% lead. Similarly, the American Research Group survey (conducted 5/14-15) indicated that Obama was tied with Clinton at 49% among the 58% of Oregon Democrats who already mailed in their ballots (the higher figure for those who had already voted makes sense given that the poll was conducted a few days later than the Survey USA poll). Among those who intended to vote but had not yet done so, Obama led 52-40%. Thus, if these two polls are correct, Obama and Clinton are in a dead heat among the votes that are already in and Obama is relying on those who have not yet cast their ballots to generate the big margin he is expected to win by.
Two things are notable about these findings from those who have already voted. First, Obama has generally performed better among early voters in other states, which might have led us to expect him to over-perform rather than under-perform among those who had already mailed in their ballots. Second, Clinton is the candidate who has generally done better among Democrats who made their decisions in the last few days of the campaign, yet she appears to be doing better among those who have already cast their ballots.
Survey USA is set to release a new poll out of Oregon on Monday. It will be interesting to see whether these patterns persist in their last poll before election day. Stay tuned...
UPDATE (5/19, 3:00pm): Survey USA has now released their final Oregon poll (interviews conducted 5/16-5/18). It shows that 77% of Oregon Democrats have now cast their ballots and Obama now has a significant 53-44% lead among this group. Of the 23% who had not yet cast their ballots but intended to, Obama led 62-34%. The size of Obama's victory in Oregon will likely depend on how many of those 23% actually do get their ballots in on time.
The figure below shows the amount of support Obama and Clinton have in both polls from those who had already voted and those who intended to vote:
UPDATE 2 (5/19, 11:55pm): Public Policy Polling also released a survey today showing Obama with a comfortable lead among both those who had already voted and those who had not yet mailed in their ballots but intended to do so. Thanks to "x curmudgeon" for pointing out the poll.