Barack Obama, 2008: 58 percent;

Mitt Romney, 2012, 38 percent:

Watched convention: 58 percent excellent or good;

Watched little of the convention: 19 percent;

Didn't watch or have an opinion: 26 percent.

51 percent: less likely to vote for Trump;

36 percent, more likely to vote for Trump;

In 2012: 38 less likely to vote for the candidate after both conventions;

In 2004 and 2008: Unnamed number less likely to vote for George W. Bush or John McCain, respectively.

73 percent, Republicans or Republican-leaning independents;

2 percent, Democrats.

Donald Trump's convention speech has received the least positive reviews of any speech Gallup has ever tested, the survey company said in a report Friday.Just 35 percent of Americans who were interviewed in the days after the speech thought it was "excellent or good," writes Gallup executive editor Frank Newport.

In comparison:Trump's ratings were higher among people who watched "a good deal" of the convention, however, compared to those who watched little or none:"But this same type of disparity has been evident in our previous reviews of reactions to acceptance speeches as well, and the key finding is that, putting it all together, Trump's speech received lukewarm ratings, based on historical comparisons," writes Newport.The overall net impact of the convention was also negative, marking the highest "less likely to vote" percentage for a candidate in the 15 times Gallup has asked the question:Republicans, however, were more likely to vote for Trump after the convention than Democrats:"At this point, we can say that although Americans' views of the Cleveland convention were not at all positive after it ended, the underlying trend data show that over the last week or so, Trump has managed to reach a milestone in his campaign: His image among Americans is now identical to that of his opponent," Newport concluded.