Republican U.S. Sen. Johnny Isakson maintains a commanding lead over his competitors in Georgia's three-man U.S. Senate race, according to a new Atlanta Journal-Constitution poll released Friday, but the contest would head into a runoff if the election were held today.

The survey shows Isakson with 47 percent support among likely Georgia voters. That puts the two-term incumbent a full 15 percentage points ahead of Democrat Jim Barksdale but still below the critical 50 percent benchmark needed to avoid a runoff.

Libertarian Allen Buckley notched 11 percent support, according to the poll. Seven percent of likely voters said they had no opinion about the race.

The survey shows Isakson with a firm lead among virtually every demographic in Georgia, including both genders and every age group and income level. Barksdale, a political newbie who has struggled to build momentum and a workable campaign infrastructure, polled best among Democrats, African-Americans and people who live in metro Atlanta.

Notably, Isakson was able to split the ticket for 18 percent of voters surveyed who said they planned to support Hillary Clinton for president. The Republican used his first two ads of the general election cycle to reach out to Democrats by emphasizing two bipartisan bills he shepherded to passage on Capitol Hill.

But the two-term incumbent still has work to do to avoid a runoff, which would occur between the race's top two finishers on Jan. 10 if no candidate wins at least 50 percent of the vote on Nov. 8. Isakson’s campaign is very much looking to avoid that scenario, which would prove to be costly and time-consuming, especially if control of the U.S. Senate hangs in the balance.

Isakson has maintained firm control of the race throughout its duration. While he lost 1 percent support in this survey compared to the last AJC poll conducted in August, he widened his lead over Barksdale by a full 9 percentage points. On the campaign trail, he's focused his messaging on his Washington work while largely keeping Barksdale, Buckley and Donald Trump at arm's length.

A Barksdale spokesman underscored Isakson's below-50-percent performance despite four decades in elected Georgia politics.

The AJC poll was conducted by ABT SRBI between Oct. 17-20 and included 1,003 registered voters, including 839 likely voters. The margin of error for the registered voter sample is 3.9 percentage points. For the likely voter sample, it is 4.26 percentage points.

Buckley's campaign manager said the Libertarian's double-digit support is notable for a third party candidate.

More results from our most recent poll: 

Read the latest on Georgia's U.S. Senate race: