For Mr. Buttigieg, the strategy of going on the attack has largely worked. He didn’t cement his place in the top tier of the Democratic primary until he became more aggressive.
His aides say they have been successful in drawing Ms. Warren and Senator Bernie Sanders of Vermont into advantageous policy fights on free college and eliminating private health insurance, which Mr. Buttigieg opposes. And in Iowa, where Democrats famously say they don’t like negative campaigning, Mr. Buttigieg has not been punished for going on the attack — in fact, he has been rewarded.
But on Thursday, Mr. Buttigieg may be in for some payback. As the polling leader in Iowa, the first caucus state, he is likely to draw substantial fire from most of the six other Democrats debating onstage at Loyola Marymount University in Los Angeles.