PROVIDENCE — President Bush is unpopular in Rhode Island, and Democrat Barack Obama holds a large lead here over Republican John McCain, according to a new Brown University poll.

Supporting the conventional wisdom of the 2008 presidential race, the Aug. 18-20 survey by Brown Prof. Marion Orr estimates Obama’s lead in Rhode Island at more than 20 points, 50.6 percent to 30 percent. Twenty percent of voters claim to be undecided. The survey of 548 registered voters has a margin of error of plus or minus 4 percent. The survey was conducted before Obama named Sen. Joe Biden as his running mate.

Ocean State voters have not favored a Republican presidential candidate since Ronald Reagan’s landslide reelection in 1984. Four years ago, Democrat John Kerry beat Republican President Bush in Rhode Island by 21 points, 60.5 percent to 39.4.

Of those who plan to vote for Obama, 75 percent say that they are “satisfied” or “excited” with their candidate, according to Orr’s poll. Fifty-two percent of McCain voters say the same.

With 79 percent of Rhode Islanders saying that the United States is on the wrong track, it’s no surprise that just 11 percent rated President Bush’s job performance as good or excellent. Twenty-one percent believe the president is doing “only fair” at his job; 67 percent rate the president as “poor.” This is a longstanding trend: a number of polls have suggested for at least two years that the president’s favorability in Rhode Island is among the lowest of any state.

Eighty percent of Rhode Islanders disapprove of President Bush’s handling of the economy.

Seventy-eight percent believe Rhode Island is on the wrong track; just 11 percent believe the state is going in the right direction.

About 14 percent approved of the way Congress is handling its duties; 67 percent disapprove, according to the survey.

Nine out of 10 of the voters surveyed said they are “very likely” to vote in November.

The campaign line for the battle between Obama and McCain is one that pits change against experience. In Rhode Island, people prefer change: 58 percent said this was the time to elect “a person who will bring greater changes.” Twenty-nine percent say this is the time for “a more experienced and tested person.”

Job creation and economic growth is the top issue for 26 percent of respondents; the Iraq war is the top concern for 13 percent; 10 percent named energy and gas prices as their top concern. Illegal immigration was the top concern for 5.4 percent.

marsenau@projo.com