A national polling firm released poll results yesterday that found that U.S. Sen. Daniel Akaka holds a slight edge over U.S. Rep. Ed Case in the Democratic primary for Senate among all likely voters, while a Hawai'i firm that surveyed likely Democratic primary voters showed Akaka with a double-digit lead.

Rasmussen Reports, an Asbury Park, N.J., firm, conducted an automated poll of 500 likely voters on Monday and had Akaka at 47 percent, Case at 45 percent and 8 percent undecided. The margin of error was 4.5 percentage points.

The OmniTrak Group in Honolulu interviewed 399 likely Democratic primary voters by phone in late July and early August and had Akaka at 55 percent, Case at 35 percent and 10 percent undecided. The margin of error was 5 percentage points.

The polls track the impressions of political analysts and some party insiders, who believe the race is closer among all voters than among likely Democratic primary voters. An Advertiser poll in June found Akaka with an 11-point lead among likely Democratic primary voters.

Voters will have the choice in September whether to pull a Democratic or Republican ballot.

The Rasmussen poll also found that the war in Iraq and the economy were the most important issues for Hawai'i voters.

"I agree that these are among the crucial issues for Hawai'i voters' consideration in this vital election. I want to stand up with my opponent on statewide media and across our state and debate these issues so that voters can make their choice," Case said in a statement.

Akaka's campaign is still weighing debate offers.

"We're going to continue to work hard every day," said Elisa Yadao, an Akaka campaign spokeswoman. "While we're grateful both of these polls showed us ahead, we're not taking anything for granted."

Reach Derrick DePledge at ddepledge@honoluluadvertiser.com.