So much for that bump.

Republican presidential nominee Mitt Romney saw his approval numbers barely budge after accepting his party's nomination on Thursday. Americans who said they were more likely to vote for Romney after the convention were effectively canceled out by an almost equal percentage of people who said they were less likely to vote for Romney, according to a new Gallup poll.

Presidential candidates from the two main political parties typically see a brief surge in popularity after their party conventions, and Gallup found that Romney's two-point boost was the lowest of any convention since 1992, although the two previous Republican nominees -- John McCain in 2008 and President George W. Bush in 2004 -- also saw only small, single-digit increases in the polls.

Republicans were energized by the convention, with more than 80 percent saying they were more motivated to vote for Romney than they were before the convention. This development was counterbalanced by the three-quarters of Democrats who said they were less likely to support the Republican nominee as a result of the Rebublican convention. Among independents, it was a wash: about a third each said they were more likely to vote Romney, less likely or unsure. 

A separate Reuters/Ipsos poll confirmed Romney's vanishing convention boost, finding that he had slipped a percentage point behind President Obama after registering a similarly slender lead on Thursday.

Romney also got low marks for his speech, a straightforward address in which he touched on his personal history before emphasizing the fact that President Obama had let America down. Gallup found that the share of Americans who rated his speech as "good" or "excellent" was the lowest since Bob Dole's 1996 acceptance speech.