Lawrence city commissioners tonight are expected to approve the purchase of a west Lawrence laboratory building as part of a plan to keep and attract promising bioscience companies.

Commissioners are being asked to give staff members the authority to prepare documents to issue $2.9 million in bonds to purchase and renovate the former Oread Labs building near Bob Billings Parkway and Wakarusa Drive.

A portion of the building would be leased to CritiTech, a Lawrence-based drug development company that needs space to expand. The remainder of the building would be used to attract other bioscience companies to the city.

The plan calls for lease payments to pay for the bulk of the $2.9 million in project costs. An agreement up for approval today contemplates that the city and county would be equally responsible to cover any shortfalls.

Also on the commission’s agenda is a discussion about what the city should adopt as its legislative priorities for state lawmakers in 2010.

Commissioners meet at 6:35 p.m. today at City Hall, Sixth and Massachusetts streets.