Amid heightened campaign activity in the final three weeks before the Democratic primary, the four candidates vying to replace retiring New Haven Mayor John DeStefano Jr. are sparring not just over the substantive issues defining the election but also over their respective chances of winning.

The summer months trimmed the field of mayoral hopefuls, turning a once-seven-candidate race into a four-way contest to succeed the city’s longest-serving mayor. Though New Haven residents will not elect a new mayor until November, the Democratic primary — scheduled this year for Sept. 10 — has long been decisive, owing to a dearth of Republican challengers in the general election.

In contrast, this year’s race is shaping up to be one of the most competitive in decades: Three of the four remaining candidates said they will not treat the primary as definitive.

Ward 10 Alderman Justin Elicker FES ’10 SOM ’10 and Henry Fernandez LAW ’94, CEO of the consulting firm Fernandez Advisors and former New Haven economic development administrator, said they will run as independents in the general election should they lose the primary. Hillhouse High School Principal Kermit Carolina said he has “left that option open.”

The only candidate banking on a primary victory is Connecticut State Sen. Toni Harp ARC ’78, positioned as the front-runner by endorsements from Connecticut Gov. Dannel Malloy; Yale’s UNITE HERE Locals 34 and 35, union groups that have acted as powerful vote-pulling organizations in the city; and a majority of the city lawmakers on the New Haven Board of Aldermen.

“I’m far ahead of the other three candidates,” Harp said in reference to polling she said her campaign conducted roughly three weeks ago. “Henry and Justin are neck and neck from what I can tell, and then Kermit trails both of them.”

Elicker said his polling indicates he has “double the support of [Fernandez],” though he said he trails Harp considerably.

Both Harp and Elicker declined to reveal exact polling figures.

Fernandez and Carolina — who have not conducted polling — dismissed the other camps’ numbers, saying their own measurements of support derive from conversations with voters.

“One of the major problems for anybody who’s touting polling at this point is the significant number of people who are still undecided,” Fernandez said.

He said accurate polling would cost $30,000, a price none of the candidates have been willing to pay.

Carolina said his polling takes the form of “face-to-face conversations with residents,” which he said have made him “confident about our chances of victory.”

Both Elicker and Fernandez said their chief opponent is Harp.

“At the end of the day, the race is going to be between myself and Toni Harp,” Fernandez said. “Alderman Elicker is a nice guy, but he’s never run anything other than his campaign for alderman. The first time you have responsibility for hiring and firing people should not be when you have a workforce of 4,000 people.”

Elicker contrasted his experience on the Board of Aldermen’s Budget Committee with Harp’s as a state senator co-chairing the Appropriations Committee. He said he has been working to ameliorate the city’s budget woes for the last three years, while “Harp has a track record of putting both the state and the city in a dangerous fiscal position.”

The Harp campaign fired back with a press release holding that Harp helped balance the state’s budget after the 2008 recession and alleged that Elicker is “dangerously unaware of how budgeting works.”

Both Carolina and Elicker said one of their first tactics in attempting to balance the budget would be to meet with the city’s department heads to identify possible cuts. Carolina also said he would seek pension reform.

Fernandez said the city’s budget problems — represented by a $500 million debt balance, the repeated downgrading of the city’s credit rating and the tripling of pension costs — merit more significant measures: controlling expenditures and addressing pension account deficits in the short term, and fostering economic development to build a more sustainable tax base in the long term.

In addition to this week’s intense focus on fiscal issues, all four candidates listed public safety, job growth and education as the primary issues facing the city.

Drew Morrison ’14, a volunteer for Elicker, said the two-term alderman is the only candidate who has detailed “research-based solutions” to combat the problems ailing the Elm City.

“Justin is taking a policy focus and grassroots approach to this campaign,” Morrison said, citing campaign finance reports released in July indicating that Elicker had raised roughly 80 percent of his contributions from New Haven residents, in comparison to Harp and Fernandez, both of whom have raised the majority of their funds from outside of the city.

Fernandez, who led the funding race with $177,081 by the July 10 filing deadline, defended his donor base by saying contributions from U.S. senators and congressmen are indicative of his breadth of experience.

Carolina — who, along with Elicker, is participating in the city’s public campaign finance system — said fundraising remains a struggle for his campaign.

The general election will be held on Nov. 5.