Members of the Bellevue City Council agreed on Monday to deliver a message to Sound Transit’s Board of Directors that they are encouraged by recent progress in negotiations over the future East Link light rail project.

A majority of the council has favored a light rail route in South Bellevue, called B7, that would run along Interstate 90 and I-405 into downtown, while Sound Transit has supported a route called B2M that would run parallel to Bellevue Way and 112th Avenue Southeast.

The two sides are also trying to work out an agreement that would pave the way for a downtown light rail tunnel, which is estimated to cost about $300 million more than a street-level alternative. Bellevue wants the tunnel but Sound Transit has asked the city to pay up to $150 million of “in-kind” contributions toward its construction.

Councilmember Jennifer Robertson will attend Sound Transit’s Board meeting on Thursday, when the transit organization could announce its final route preference for East Link. Councilmembers expressed cautious optimism that progress can be made on issues such as engineering, environmental review, mitigation, public outreach and funding for the downtown tunnel.