A new marathon in Newport has the potential to generate £1.1m for the local economy in the next three years, according to a council report.
About 10,000 runners have signed up for ABP Newport Wales Marathon and a 10k race on 29 April.
Organisers Run 4 Wales estimate there will be a crowd of 20,000 people who the council said would boost traders.
Newport council is being asked to pay £90,000 towards the race until it is expected to be self-sufficient by 2020.
The Welsh Government has agreed to provide up to £120,000 over the same period, said the report.
The new marathon comes after the organisers had tried to hold a marathon in Cardiff and Vale of Glamorgan in 2017 but could not settle on a route.
Boss Matt Newman said Newport offered the "perfect landscape" for a flat, fast race.
Newport's half marathon was cancelled twice this year because of snow and then freezing conditions, with no feasible date found to run it in 2018.
The report said: "The initial agreement is for support over a three year period only, by which time the event should be self-sufficient and sustainable without a need for additional public funding."
Newport council's cabinet is due to discuss the funding bid with additional race support from local authority officials at a meeting next week.
Run 4 Wales chief executive Matt Newman said he hoped the marathon and 10k could become a "permanent fixture" on the Welsh sporting calendar.
"The city of Newport and the surrounding areas provides the perfect landscape for a flat, fast route for elite and novice runners alike," he added.
Associated British Ports is the race's title partner.
Run 4 Wales, a not-for-profit business set up in 2012 to develop the Cardiff Half Marathon, runs a host of other events and invests profits in sporting activities.
Last year's Cardiff Half Marathon became a 25,000 sell-out for the first time.