City of Napa voters may end up deciding the fate of the proposed Kimpton hotel on Solano Avenue at the November election.

A hotel workers’ union, Unite Here, submitted referendum petitions Thursday with 5,200 signatures.

If 3,630 of them belong to registered city voters, the Napa City Council would be obligated to kill the project, downsize it or put the fate of the 196-room hotel to a public vote.

Unite Here mounted a petition drive in June after the hotel developer, McCuen Properties of Sacramento, and the proposed operator, Kimpton Hotels of San Francisco, failed to sign a “neutrality agreement” promising not to fight union organizing of its workers.

The union, which has offices in San Francisco, hired a company to gather the petition signatures at local shopping centers, while aligning itself with some neighbors who feared the hotel’s traffic and noise impacts.

Several council members accused the union of “strong-arm tactics” and “playing hardball.”

A developer representative said the Kimpton was willing to negotiate a neutrality agreement, but not on such short notice.

Union officials say they are fighting for the rights of workers to earn strong wages in Napa’s growing hospitality industry.

City Clerk Sara Cox said the union turned in more than the necessary number of signatures required to force a referendum, but it is unknown how many are valid. The law requires 10 percent of registered voters, who numbered more than 36,000 at the June primary, to sign the referendum petition.

The city will hire the county elections office to verify the signatures, Cox said Monday. Many people sign petitions believing they are registered voters, but are not, she said. Others think they live in the city, but do not.

Rather than attempt to verify all 5,200 signatures, John Tuteur, the county registrar of voters, intends to sample 500 signatures. That will cost the city about $1,000, he said.

The law gives his office 30 working days to verify signatures, but this could be done much sooner using the sampling technique, he said.

The council meets on July 15, but this may be too soon for it to receive the referendum petitions, Cox said. The next council meeting is Aug. 5.

The city would have to decide to put the Kimpton to voters by Aug. 9 if the referendum is to qualify for the November election, Tuteur said. Otherwise, the city might have to set the matter for a special election, he said.

Napa City Attorney Michael Barrett said the petitions appeared at first blush to meet the procedural requirements for a referendum election. His office will further analyze whether the Kimpton project meets other state requirements, he said.

Union spokesman Owen Li reported Monday that the union had been able to gather more than 5,000 signatures in just a few weeks’ time.

“Based on conversations with Napa voters in the course of gathering signatures, it is clear that many Napa residents are concerned about issues related to the rapid growth of the hotel industry in the city,” he said.

The union wants hotels to pay a “living wage” of $15 to $17 per hour so that workers can afford to live in Napa and afford health insurance.

Both the Kimpton, which the council approved on a 3-2 vote on June 3, and the proposed Ritz-Carlton hotel, which comes before the council on July 15, are high-end brands that can afford to pay good wages, Li said in an earlier interview.

Local attorney Kevin Teague, representing McCuen and Kimpton, said his clients “plan to defend the city’s approval of the project and the two years of process we went through.”

  Kimpton officials have pledged to pay higher than average wages, while hiring locally and offering training, he said.

“I think it’s unfortunate this process is being used by the union. It has the potential to take away good jobs for the people of Napa,” Teague said.

The Kimpton is proposed for the southwest corner of Solano Avenue and Wine Country Avenue. The property is now occupied by the 115-room Chateau hotel which would be torn down.

As a condition of approval, the developer would have to build a right-turn lane on Wine Country at Solano and contribute money toward a traffic light, which would be installed in coming years.

The developer estimated that the project would produce $1.3 million in annual bed tax revenue for the city.