Notice the unmistakable trend?
All polls with 1000 or more respondents favor Romney; all polls with smaller than 1000 respondents favor Obama (or are tied).
Statisticians will tell you that the larger the sample size, the more reliable the poll. This fact is reflected in RCP’s “Margin of Error” (MoE) column, which shows a lower margin of error, and thus a greater level of reliability, for the large-sample pro-Romney polls. Each and every pro-Obama poll has a higher margin of error, and is thus less reliable.
These are the facts as they currently stand, and they’ve been true like this almost every day since soon after the first debate when Romney surged in popularity.
The question we must now ask ourselves is why only the weak polls with low response rates favor Obama.