A candidate running for deputy mayor of St. John's is accusing her opponent of resorting to attack advertising.

Shannie Duff and Keith Coombs, two longtime municipal politicians, are squaring off against each other for the position, with the state of the city's finances emerging as a contentious point.

Keith Coombs is running for the deputy mayor position on St. John's city council. (CBC)

In his campaign ads, Coombs says the city is expected to have an annual surplus of $11 million for each of the next four years, for a total surplus of $44 million, and that he wants the money to go back to the taxpayers.

But Duff has countered that Coombs's claim of a large surplus is irresponsible and unsubstantiated.

She said Coombs is relying on an internal planning document, which doesn't account for inflation, or an expected increase in payroll and tenders that could come in higher than expected.

Shannie Duff is campaigning to become the deputy mayor of St. John's. (CBC)

Coombs responded with radio and television ads that say Duff doesn't understand the city's finances.

Duff said she does understand the finances, but that Coombs is making unrealistic assumptions.

"When you're trying to predict a surplus and say you're giving it back to the taxpayer four years out," said Duff, "all I can say to that is I think he should be picked up immediately by the federal and provincial governments, because they would love to have someone with that kind of a crystal ball."

Municipal voters go to the polls on Sept. 29.