By Jason Horowitz

February 4, 2008 | 3:56 p.m

WORCESTER, Mass.—In a slightly altered stump speech delivered here this afternoon, Hillary Clinton challenged Barack Obama by arguing that it was more worthwhile to use unity to reach a goal rather than just espouse unity for unity’s sake.

“There are differences between me and my opponent—differences in approach and vision an understanding of what it is going to take to make the changes that we want,” said Clinton. “You know change is hard. I wish it were easy. I wish all you had to do was just say it’s going to happen, and it would materialize. But it’s going to take hard work. It’s going to take every single one of us being committed to a different future for our children.”

“And unity is important, but unity for what, is more important,” said Clinton. “Unity for a strong and prosperous middle class?”