From the new ABC poll on The favorability of the Presidential candidates:
Night-to-night data indicate a sizable boost for Romney, and drop for Obama, on Thursday night, a day after their first debate, which Romney widely is seen as having won. But both of those trends subsequently subsided in this poll, conducted Thursday through Sunday. The net effect is slight at best. Romney is now seen favorably by 47 percent of registered voters overall, unfavorably by 51 percent; Obama’s rating is better, 55-44 percent.
Changes for both candidates from their pre-debate levels (Romney 44-49 percent, Obama 52-45 percent) are not statistically significant, given the surveys’ margin of sampling error.