Hillary's accusation that Obama stole key phrases from speeches by Massachusetts Governor Deval Patrick is significant because it has the potential to strike at the heart of Obama's central political asset, namely the widespread perception (held even by those who don't share his views) that he's a "man of integrity."
Is it acceptable to borrow language from another politician, without attribution, and then, when called out, explain it by saying that the guy who first spoke the words said I could use it? The fact that Deval himself laughs off the accusation and supports Obama's use of the material takes a lot of the edge off Clinton's charge. Will some black voters view Hillary's accusation as yet another playing of the race card? ("Tell the white girl to leave the two brothers alone.")
The key political question is whether Hillary's punch will resonate with upper income, well educated white voters who comprise a significant portion of Obama's coalition. On the eve of Wisconsin's pivotal primary, will Madison liberals with masters and doctoral degrees view Obama's use of Patrick's words as "plagiarism" or as a matter of rhetorical resonance between two articulate African American politicians? Much will depend on how both campaigns spin the issue in the hours before Wisconsin voters go to the polls. And on whether the mainstream media sides with Obama or Clinton.
As usual, Clinton's argument comes with no small degree of hypocrisy. She shamelessly lifted these phrases from Obama: "It's time to turn the page," "I'm fired up and ready to go," and "Yes we can!"
UPDATE: Obama has acknowledged he "should have" credited Patrick. Will Hillary make the same concession to Obama? Put your overcoat on when that happens. It will be a frigid day in hell.