Julie Levin/KJZZ

Chase Field in downtown Phoenix.

The Arizona Diamondbacks are threatening to sue Maricopa County and leave downtown Phoenix unless Chase Field is upgraded.

In a letter to county officials Thursday, the Diamondbacks say the county has failed to make $187 million in repairs to the ballpark that opened in 1998 when Arizona joined the National League as an expansion franchise.

However, Maricopa County Stadium District Director Daren Frank said the county’s portion is more like $32 million. He said they were taken aback by the Diamondbacks’ request to amend the long-standing agreement.

“They have been over the years asking for certain things. A reduction in rent namely being one of them," Frank said. "But never have they asked directly for any sort of amendment to the agreements that we’ve lived with for the past 17 years.”

Diamondbacks President Derrick Hall says the team doesn’t want to leave.

“Our preference would be to stay at Chase Field. But, before we can determine whether retrofitting or renovating Chase Field is the answer, we feel like we owe it to ourselves since we know that they can’t fulfill their end of the bargain, we need to at least go and see what those options are to play elsewhere and see what other partners may be out there," Hall said.

County officials say taxpayers built the ballpark with $238 million in sales taxes, Frank said there should not be more more onus put on the taxpayers.

The Diamondbacks' contract with the county runs through 2028, and the team is prohibited from trying to move until 2024.

The Associated Press contributed to this report.