Not sure about Powerline as a source? They state they are conservative, however, a snippet about their president has me questioning just how unbiased they are.

"He has appeared as an commentator on NBC, CBS, Fox News, CNN, CNBC and Sky News Australia, and is a frequent guest and guest host on national radio programs. John has lectured at Dartmouth College, Harvard Law School, Carleton College, St. Olaf College, Macalester College and the University of Minnesota."