Mitt Romney’s stumble in the Deep South Tuesday rekindled worries within the GOP about his weak hold on the most conservative corners of his party.

But the Republican presidential nominating contests so far have also highlighted an important Romney asset: He has shown the most muscle in states that will determine who takes the White House in November.

His defeats, which include losses Tuesday to Rick Santorum in conservative Alabama and Mississippi, have come largely in states that any Republican nominee is almost certain to win this fall.