WASHINGTON – For a day, at least, President Barack Obama and Republican Mitt Romney stopped assailing each other and spoke as heartbroken parents.

The Colorado movie theater massacre upended the presidential campaign on Friday, obliging both candidates to cast aside the increasingly bitter tone of the race and reach for a rare moment of American harmony. Yet the moment itself was a political test, for a president charged with consoling a nation and for a challenger needing to show that he could rise to the occasion.

"There are going to be other days for politics," Obama said from one key electoral state, Florida. From another one, New Hampshire, Romney said much the same.