Incumbent Sen. Brian SchatzBrian Emanuel SchatzOvernight Tech: AT&T chief takes the stand to defend merger | Facebook keeps most users out of EU data law's reach | HUD reopens probe into Facebook housing ads | Venture capital firms go to bat for cryptocurrencies Facebook investigated over alleged housing discrimination Senate confirms Trump’s pick to lead NASA MORE (D-Hawaii) leads his Democratic challenger Rep. Colleen HanabusaColleen Wakako HanabusaFormer Sen. Daniel Akaka of Hawaii dies at 93 Zinke defends use of Japanese word: How could saying good morning 'be bad'? With bills on the table, Congress must heed the call to fix our national parks MORE (D-Hawaii) by 5 percentage points, according to a new poll.

A Civil Beat Poll released Tuesday found 44 percent of Hawaii voters support Schatz, while 39 percent said they’d vote for Hanabusa. Sixteen percent said they’re undecided.

This is the fourth poll Civil Beat has conducted for this race, but the first one in which one candidate has gained a slight advantage, Civil Beat said. Previous surveys suggested the race was tied.

A recent survey conducted by Public Policy Polling for Democracy for American, a group that backs Schatz, indicated he led Hanabusa by 15 percentage points.

Both lawmakers are competing for the Democratic nomination in the Aug. 9 primary. President Obama has endorsed Schatz.

Hawaii Gov. Neil Abercrombie (D) appointed Schatz to the Senate in late 2012, after Sen. Daniel Inouye died.

Abercrombie reportedly received a “dying wish” from Inouye, just after he died, urging him to appoint Hanabusa as his successor. She was elected to the House in 2010. 

The latest Civil Beat poll surveyed 840 registered Hawaii voters May 18 to 19 with a 4.3 percent margin of error.