SurveyUSA Says Senate Race Tied

A new poll from SurveyUSA has Cardin tied with Steele but O'Malley leading Ehrlich by 6 points. As this chart from Pollster.com shows, SurveyUSA is a real outlier in Maryland Senate polling. Both of their polls show the race essentially tied while all other polls give Cardin a lead outside of the margin of error. See a similar chart on RealClearPolitics to see exactly how different SurveyUSA's results are from those of other outfits.

The real question of course is why. Essentially, SurveyUSA shows Steele tied because Steele gets around one-quarter of the black vote in their polls. While high for a Republican, one-quarter is not out of the range of possibility. Is SurveyUSA on to a trend that other pollsters have failed to capture or are their results off for some methodological reason or just the incredible bad luck of two rogue polls in row?