Perhaps as important as the policies of a presidential candidate is the company he keeps. The candidates like to brag about such company when it suits them. For example, Sen. John McCain touts his frequent meetings with foreign heads-of-state to illustrate his national security leadership. And in response to the recent economic crisis, Barack Obama has made it a point to surround himself with folks like former Federal Reserve chairman Paul Volcker.

But there’s the flip side, too. Obama’s brief association with Jim Johnson, former chairman of fallen giant Fannie Mae, became the subject of an attack ad. Meanwhile, McCain has been attacked for his ties with lobbyists.

So it shouldn’t be surprising that Obama is catching more heat on his relationship—whatever it was—with the controversial figure Bill Ayers during their time together working in Chicago for the Annenberg Challenge. In an opinion piece titled “Obama and Ayers Pushed Radicalism on Schools,” Stanley Kurtz writes in the Wall Street Journal that some original research he did shows the pair were far more intertwined than the Obama campaign would like others to believe.

Kurtz expands on the commentary even more in this piece in the National Review Online, in which he reprints a lengthier response from the Obama campaign.

His commentaries add to the existing work that’s already been written about Obama and the Annenberg challenge. Education Week‘s David Hoff wrote about the subject in March 2007 and Mark Walsh wrote about Ayers in April of this year. Earlier this month, the New York Times examined Obama’s role with Annenberg and Ayers.