AMHERST — A general contracting bid below the $36 million estimate for expanding and renovating the Jones Library was received by the town by Thursday’s deadline.

At $35.77 million, the bid from Fontaine Brothers Inc. of Springfield, one of two submitted for the project, is $231,000 below the advertised cost of the work.

Robert Pereint, special capital projects coordinator for the town, wrote in an email that Fontaine is the apparent low bidder, but its package is still being reviewed. Pereint added that electrical sub bids are due on Nov. 7 at 2 p.m., meaning the final contract amount would be adjusted up or down based on those bids.

Fontaine was the lone bidder last spring when its $42.7 million bid was rejected due to being at least $6.5 million over the money available for the project. The total project costs for enlarging the building from 48,000 square feet to 63,000 square feet have been pegged at $46.1 million, when factoring in expenses such as furnishings and architectural fees.

But with project expenses to date and contingency costs, the new low bid places the total project cost about $1.6 million under the $46.1 million bond cap approved by the Town Council, according to Library Director Sharon Sharry.

“We are pleased the project will continue to move forward,” Sharry said. “I’m grateful for the architects, building committee and whole team working to see this through.

“Through many delays, our original vision for a safe, accessible, welcoming, and sustainable library remains relevant and necessary,” Sharry said.

“There is more work to be done, but this news bodes well for this project to move forward,” said Town Manager Paul Bockelman.

Should the bid be awarded by the town, Bockelman would sign a contract to proceed. In addition to the electrical sub bids, the town is also continuing with a Section 106 federal review to resolve adverse effects from the project on historical aspects of the building through a memorandum of agreement that still needs to be finalized.

The project is being paid for through a combination of community fundraising, more than $15 million from Massachusetts Board of Library Commissioners grants and $15.8 million from the town.

But Maria Kopicki, a representative of Save Our Library, a group that is circulating a petition calling on the town to abandon the project in the face of its high cost, said there remains a multimillion-dollar fundraising gap, even for the budgeted amount.

“Between cost overruns and the Section 106 process that may require additional spending or further loss of funding, the low bid is very likely to underestimate what the proposed project would actually cost,” Kopicki said. “Now is the time for town leaders to consider the financial implications of a complicated construction project not going as planned.”

The other bid received by the town’s deadline was for $38.91 million from J&J Contractors Inc. of North Billerica.

Both companies were also bidders on the project to construct a new elementary school, though low bid for that project, which is being challenged at the attorney general’s Fair Labor Division, was awarded to CTA Construction Managers of Waltham.

Since rejecting Fontaine Brothers’ initial library building bid in the spring, trustees and the Jones Library Building Committee, with Finegold Alexander Architects and the Berkshire Design Group, have made a series of so-called value engineering changes to the project to reduce costs and bring it in line with the funding that is available.

Save Our Library’s petition cites not only the growing price tag, but the possible impacts on the original 1928 portion of the Amity Street building and questions around whether the final project will meet Amherst’s net-zero energy goals.

The project, though, remains to renovate the original library building, demolish the 1990s-era addition and construct an addition that will enlarge the entire building, with library to operate out of a temporary site during the construction.

Among the changes to the plans are a switch to a conventional steel structure rather than cross-laminated timber, removing the roof monitor, or skylight, that had been visible from Amity Street and scaling back landscaping plans. The changes in landscaping include no longer having Goshen stone benches, eliminating a children’s courtyard, and removing the granite cladding on the retaining wall near the Strong House museum, instead replacing that with “a color admixture or future mural by others.”

The project, though, does retain use of synthetic slate roofing and replacing the windows in the 1928 building with modern look alike windows, as in the original plans.

Included within the project will be other utility and infrastructure modifications, landscaping, hardscaping, parking and pedestrian area improvements. The building will eliminate the use of fossil fuels, becoming net zero-ready, more efficient and sustainable than the current building; preserve the look and feel of the historic building and open spaces currently unavailable to the public; and provide additional, climate-controlled secure archives for Special Collections, including a permanent home for the town’s Civil War tablets.

The project will also include a dedicated teen space and better room for the English as a Second Language program, and it will correct numerous problems with heating, cooling and ventilation systems, and meet the town’s climate goals.