REVERE – Mayor Thomas Ambrosino said a few more chips need to fall where they may before he can gauge how the partnership between two local racetracks benefits the city.Suffolk Downs principals Richard Fields and Joseph O’Donnell and Wonderland Greyhound Park owner Charles Sarkis announced the merger on Wednesday, making it clear they want to preserve jobs at both tracks and “strengthen the effort to bring a resort-style casino to the East Boston-Revere area.”Ambrosino said those goals will be shaped by the success or failure this November of a ballot question phasing out dog racing and renewed interest, if any, by the Legislature in bringing casinos to Massachusetts.”There are too many uncertainties right now. A year from now the picture will be a lot clearer,” Ambrosino said.State Rep. Robert DeLeo, a chief proponent of bringing slots to Wonderland, is optimistic about the merger but said job preservation and local interests are his immediate concern.”I will be monitoring the situation to make sure the interests of both are met,” DeLeo said Wednesday.The city’s interest in getting Wonderland to pay off $800,000 in back taxes and other bills will be addressed in the merger agreement between the two tracks.Ambrosino noted that city ordinances allow Wonderland to present a tax payment plan to the License Commission next week when the commissioners meet to consider revoking the track’s licenses for nonpayment of taxes.”Eventually our taxes are going to be paid,” Ambrosino said.In announcing the merger Wednesday, Sarkis said the two years worth of merger talks focused in part on job preservation.”All along during discussions with Suffolk Downs, we had one big goal in mind: protect the jobs of nearby residents who, in many cases, have spent their whole lives working at this facility,” Sarkis said.Sarkis and Fields said their agreement gives Suffolk the option of purchasing Wonderland and added: “Both facilities will remain separately owned and operated while they work collaboratively to expand the gaming and entertainment opportunities available to their patrons, expand employment opportunities for their workers and increase revenues for local and state coffers.”The purchase option potentially sets the stage for Wonderland to become prime development property in the city’s center bordering the planned commercial and residential development around Wonderland station.Ambrosino said the Wonderland development, slated to get underway early in the next decade, is separate from any potential development at Wonderland. However, he said the two projects, once they unfold, must be compatible.Track representatives estimate both facilities employ 2,700 people including track workers and individuals employed in the racing dog and horse industry.The organization pushing for the humane treatment of dogs through a phase out of racing said state estimates of employment at seven state racetracks totals 707 workers.Carey Theil referred to a May 27 estimate prepared by state labor officials in citing that estimate.”We’re sympathetic to people who work in this industry. That’s why the referendum includes a 14 month phase out period,” Theil said.