Residents of San Diego have voted against building a new Chargers stadium funded by an increase in hotel tax.
A two-thirds majority was required for "Ballot Measure C" to pass, but with over 85% of votes counted, the number was only at 42.5%.
In an open letter, Team owner Dean Spanos thanked the Chargers fanbase, but was non-committal on the future of the franchise.
"Despite the fact that Measure C failed to receive a two-thirds majority, I wanted to reach out right away with a very sincere thank you for your loyal support as a fan and for considering our initiative.
"In terms of what comes next for the Chargers, it's just too early to give you an answer. We are going to diligently explore and weigh our options, and do what is needed to maintain our options, but no decision will be announced until after the football season concludes and no decision will be made in haste."
The ballot proposed that the $1.8billion stadium would be funded in the majority by increasing hotel occupancy tax from 12.5% to 16.5%, raising $1.15billion, combined with a $650million joint pledge from the NFL and Chargers organisation.
Spanos had proposed a "Super Bowl ready" stadium, combined with convention centre and music venue, which could be available for other events 300 days a year.
However, the defeat spells uncertainty for the future of the Chargers. The team currently play in the outdated Qualcomm Stadium, which they have inhabited since 1967.
The organisation has the opportunity to move out of San Diego and join the Los Angeles Rams at their new facility in Inglewood. However, Spanos had been committed to staying in San Diego, and changed his stadium plans in an attempt to convince mayor Kevin Faulconer.
Despite Faulconer's support, residents have opted against the ballot, and Spanos now has until January 15 to make a decision whether to follow the Rams.
Should the Chargers decide not to move upstate, the Oakland Raiders also have an option on a ground share with the Rams.
The uncertainty will make it an uneasy second half of the season for Chargers fans, who will hope there is still NFL to watch in San Diego come 2017.