The finish line is drawing nearer to register for the ING Miami Marathon and Half Marathon.

For the first time since the race was created in 2003, organizers believe they might have a sellout for the 10th running of the event, one month away on Jan. 29.

“It’s not a normal year for us,’’ race director David Scott said. “We’re over the 20,000 [combined] mark. We just think that if the numbers continue the way they’ve been, that we will sell this race out. You can feel the excitement. A number of people have been changing their registrations from the half to the full.’’

The races begin together at 6: 15 a.m. (6:05 a.m. for wheelchairs) in front of the AmericanAirlines Arena and will follow the same course as last year — weaving through Miami, South Beach, Coconut Grove, down Bayshore Drive, over the Rickenbacker Causeway’s William Powell Bridge and back toward the finish at Bayfront Park. Scott said once the race reaches a combined field of 25,000, all registration will end. As of Wednesday, 15,032 had registered for the half marathon and 5,096 for the full for a total of 20,128.

Last year’s numbers at the same time: 11,654 for the half and 4,035 for the full. The inaugural race drew 3,400.

“We’ve become a destination event,’’ said Scott, who noted that participation from countries such as Mexico, Brazil and Venezuela has risen. “We even have a travel group coming out of France.’’

The accompanying Nissan Health & Fitness Expo during race weekend is once again at the Miami Beach Convention Center and will be open from noon to 7 p.m. Jan. 27 and 10 a.m. to 6 p.m. Jan. 28.

Scott said he’s hoping that 2011 men’s champion Tesfaye Sendeku Alemayehu (2:12:57) of Ethiopia will return. Last year’s women’s champion, Alena Vinitskaya (2:44:38) of Belarus, was injured earlier this month.

Registration is $110 for the marathon and $85 for the half through Jan. 20. After that, the cost is $125 for each distance. Scott believes both events could be sold out by then.

For more information on the marathon weekend, which includes the Tropical 5K (starts at Watson Island and ends on South Beach) at 7:30 a.m. Jan. 28, go to www.ingmiamimarathon.com.