National poll results don’t mean much in April, since more than 40 states have already held their primaries, but Gallup’s trends may hold more significance than the remaining primaries indicate. Barack Obama lost the top spot to Hillary Clinton for the first time in a month, and after Wednesday’s debate performance, the trend may become even more pronounced:

Gallup Poll Daily tracking shows that Hillary Clinton now receives 46% of the support of Democrats nationally, compared to 45% for Barack Obama, marking the first time Obama has not led in Gallup’s daily tracking since March 18-20.

These results are based on interviewing conducted April 16-18, including two days of interviewing after the contentious Wednesday night debate in Philadelphia and the media focus that followed. Support for Hillary Clinton has been significantly higher in both of these post-debate nights of interviewing than in recent weeks. The two Democratic candidates are now engaged in intensive campaigning leading up to Tuesday’s Pennsylvania primary and are under a continual and hot media spotlight, increasing the chances for change in the views of Democrats in the days ahead.

Assuming this holds up, the results could spell trouble for Obama. Hillary has been trying to make the electability argument for several weeks among the superdelegates. If Obama continues to decline in national polling, that argument could resonate, especially given the steep decline this month in Obama’s polling He has lost seven points in the last two weeks, six of those in the last four days. That could give considerable heartburn to the superdelegates, who may very well wonder whether Obama’s terrible performance this week could presage a complete general-election collapse.

Obama has to show that he can handle tough questioning, and not just to get through the primaries against Hillary Clinton. He can keep claiming to have been victimized by ABC, but Americans don’t usually elect people for whining. He has to overcome a little hostility from the press, or voters will rightly wonder whether he can handle himself under much more pressure once ensconced in the White House. Even the superdelegates may be asking themselves that question.