Romney's poll numbers have hoovered around 22% + or - 2 points or so over the last month.
You can ignore one poll as a possible outlier, but when every single poll for a solid month from different pollsters using different methods shows the race at a particular point... you can be pretty darn sure that's where the race is at.
And when the first poll out of the gate following a less than stellar debate performance finds his support basically unchanged...that's significant.