A note to the Republican presidential candidates heading to Washington for the Conservative Political Action Conference: Some of the events could make you uncomfortable if you’re planning to tack to the center in your general election campaign.

Three of the GOP candidates — Mitt Romney, Newt Gingrich and Rick Santorum — will address the largest annual gathering of conservatives on Friday. But Thursday brought a provocative panel discussion: “The Failure of Multiculturalism: How the Pursuit of Diversity Is Weakening the American Identity.”

One of the panel’s speakers was conservative author Peter Brimelow, whose book, Alien Nation, decried America’s increasing racial diversity due to immigration (legal or illegal). The Southern Poverty Law Center has identified him as a “white nationalist” and monitors his website, VDARE.com, as a hate group. (Brimelow, an immigrant from England, named his website afterVirginia Dare, the first English settler born in the New World, in 1587.)