Poll: Did GOP convention change minds?

CHARLOTTE, North Carolina (CNN) - Americans are divided on whether last week's Republican Convention made them more likely to vote for GOP presidential nominee Mitt Romney, according to a new national survey.

A Gallup poll released Monday morning indicates that four in ten adults say they are more likely to support Romney based on what they read or saw from last week's convention in Tampa, Florida, with 38% saying they are less likely to vote for the Republican challenger, and 22% saying they didn't know or the convention didn't make any difference to their vote.

Among crucial independent voters, 36% say the Republican Convention made them more likely to vote for Romney, with 33% saying no and three in ten saying they didn't know or the convention didn't make a difference.

The numbers are very close to the reaction following the Republican convention four years ago in St. Paul, Minnesota, when Sen. John McCain of Arizona was nominated for president.

By a 43%-38% margin, Americans said they were more likely to vote for McCain because of the convention. As for the 2008 Democratic convention, which was held a week earlier in Denver, Colorado, Americans by a 43%-29% margin said they were more likely to vote for Sen. Barack Obama of Illinois, the Democratic presidential nominee.

Thirty-eight percent of those questioned in the new survey said they thought Romney's Thursday night acceptance speech was excellent or good. That's down from the 47% who four years ago said McCain's speech was excellent or good and the 58% who said the same thing about Obama's address in 2008.

Gallup says that Romney's speech rated lower than any of the eight convention addresses they've tested since Bob Dole's acceptance speech at the 1996 GOP convention.

The Gallup poll was conducted August 31-September 1, entirely after the Republican convention. The survey was conducted by telephone, with 1,045 adults nationwide questioned. The poll's sampling error is plus or minus four percentage points.