To borrow a convenient word from President Obama, the process of running for the White House is evolutionary in nature: A candidate must convince their base to like them, then they must evolve to appeal to a wider audience (Etch A Sketches not included). One milepost along the traditional route a candidate takes toward the middle is a moment of putting public distance between himself and his party's most extreme supporters.
In 1992, Bill Clinton accomplished that in a speech to the Rainbow Coalition when he criticized an interview hip hop artist Sister Souljah gave to the Washington Post, in which she made racially-charged comments. George W. Bush had a similar moment in 1999, when he used the title of a Robert Bork tome to distance himself from the extreme religious right. Then-candidate Barack Obama contended with a more personal issue when he gave a speech on race in America; part of that speech was critical of the Rev. Jeremiah Wright, Obama's own (now former) pastor, and Wright's statements about the relationships between blacks and whites.
Now that he's sewed up the Republican presidential nomination, we can start looking for Mitt Romney's Sister Souljah moment. Romney has passed on other potential Sister Souljah moments, first during the Sandra Fluke controversy -- as my colleague John Aloysius Farrell pointed out -- and again this week when an audience member at one of his town hall meetings said Obama should be tried for treason.
The next opportunity for Romney to put distance between himself and his party's farthest-right base will come this weekend, when he delivers a commencement address at Jerry Falwell's Liberty University.
But Romney isn't likely to make his stand on Saturday -- and the very fact that he's giving Liberty's commencement address hints that he has to keep sewing before he can rend.