The Sonoma Marin Area Rail Transit agency is seeking up to $38 million in state cap-and-trade funds to extend passenger service to Windsor by early 2020, officials said Tuesday.

The money would fund a 3-mile extension of the rail line from Airport Boulevard north to the Windsor station.

Farhad Mansourian, SMART’s general manager, said Tuesday he feels “pretty good” about the agency’s chances. He said every member of the North Coast’s legislative delegation signed a letter supporting the application.

The voter-approved, taxpayer-supported commuter rail project originally envisioned a 70-mile route from Larkspur to Cloverdale. SMART instead is planning to bring the project online in phases, starting later this year with the debut of service on a 43-mile segment from downtown San Rafael to the Airport Boulevard station.

The rail agency late last year secured $40 million to extend the line 2.2 miles to Larkspur, with service there estimated to begin in 2018. Mansourian said SMART’s focus now is on bringing passenger rail north to Windsor, Healdsburg and ultimately to Cloverdale.

“We’re continuing to work until that vision, and what the taxpayers voted for, is accomplished,” he said.

The grant money sought for the Windsor extension is through the state’s Transit and Intercity Rail Capital Program, which invests in projects that increase transit ridership. About $440 million is available through the program, according to state transportation officials.

The grant money, which is derived from cap-and-trade auctions, seeks to combat climate change by supporting public transit projects that contribute to a reduction in greenhouse gas emissions.

SMART was awarded $11 million previously from the same account to fund the purchase of four of the slope-nosed rail cars, called diesel multiple units, that it plans to run on the line. Each car has 79 seats, with standing room available for about 80 people.

In anticipation of passenger rail service to Windsor, SMART is working with town officials on making improvements to an at-grade rail crossing at the intersection of Windsor River Road and Windsor Road, including the possibility of installing a traffic roundabout at that location.

Town leaders are reviewing designs for both the roundabout and modifications to traffic signals, according to Stuart Hayre, acting public works director.

The town recently submitted a grant proposal requesting more than $5 million for the intersection improvements.

You can reach Staff Writer Derek Moore at 521-5336 or derek.moore@pressdemocrat.com. On Twitter @deadlinederek.