OAKLAND — The A’s could be getting closer to building their proposed 35,000-seat stadium at Howard Terminal depending on how the Port of Oakland’s board of commissioners vote Monday.

The board is set to vote on whether to approve an exclusive negotiation term sheet with the A’s that would give the team four years to get land use approvals, conduct an environmental review and get everything else in order to lease the 50-acre Howard Terminal. The term sheet also lays the framework for a lease agreement, calling on the A’s to pay around $3.8 million for the first 20 years of the 66-year lease; the rent would increase after 20 years.

Port of Oakland spokesman Mike Zampa said the annual rent amount was done in private negotiations. He stressed that the term sheet — if approved — is non-binding, and that the amount could be renegotiated.

During the four years of the agreement, the port would not consider other potential bids on the property.

“What it locks in is the A’s will have the time to do their homework, and the port would not entertain other suitors,” Zampa said.

If approved Monday, the A’s will have 10 days to pay the port $100,000 to cover the staffing costs under the agreement. They would pay an additional $150,000 after the first year, $200,000 after two years an $250,000 after three years.

Some are urging the board not to approve the agreement. Mike Jacob, vice president of the Pacific Merchant Shipping Association, a trade group representing marine terminals and vessel operators, said he believes the A’s are getting special treatment under the proposed deal, and said other companies who lease terminals are having to pay more per acre.

The port’s largest terminal, the Oakland International Container Terminal, at 290 acres, entered into an agreement with the port last year to pay a fixed annual rent of $54.7 million plus a variable amount expected to be around $20 million. The fixed rent alone is about $188,000 per acre, which is more than twice what the Port would be requiring the A’s to pay — about $76,000 an acre.

Matson Terminal, at 75 acres, agreed last year to pay a fixed amount of $10.9 million a year, though that amount will increase over time. That’s about $145,000 per acre.

However, the A’s have agreed to pay the cost of cleaning up the contaminated site, which could carry a high price tag. Over the past century, it has housed a gas plant, another producing charcoal and also home to oil tanks. Chemicals remains in the soil and groundwater, including some known to cause cancer .

The A’s plan to build the ballpark by 2023, and build triangular buildings surrounding stadiums that would either house apartments, condos or hotels.