A poll published this week shows Senator Scott Brown (R-MA) opening a large lead on Democratic challenger Elizabeth Warren, even after previous polls showed trends moving in the opposite direction.

Published Thursday night by Suffolk University, the survey (PDF) claimed Brown holds a 9 percent lead over Warren -- surprising, given that a poll published on Valentine's Day by the thinktank MassINC found Warren leading Brown by three percent, which was within the margin of error.

Other prior polling conducted in the months leading up to the Suffolk poll found Warren with a growing lead, going from a dead-heat in Sept. to a Warren surge by Dec.

It's not immediately clear why the Suffolk University survey returned such different results, but the demographic breakdown shows that out of 600 participants, 526 were classified as White/Caucasian. Only 25 African-Americans participated, followed by 22 Latino-Americans and eight Asian-Americans.

The U.S. Census Bureau notes that in 2010, Massachusetts had a population that was 6.6 percent African-American, 9.6 percent Latino-American and 5.3 percent Asian-American -- meaning all three groups appear to be under-represented in the survey, but not by much.