NORTH BAY — Planners expect to award at least two more contracts for the construction of a commuter rail line between Sonoma and Marin counties by this summer, following the failure of an effort that could have repealed the 2008 sales tax measure that supports the project, according to Sonoma Marin Area Rail Transit General Manager Farhad Mansourian.

The two contracts – and a possible third – will join an initial contract awarded in January and account for all of the work necessary to complete the so-called “Initial Operating Segment” of SMART, a 38.5-mile stretch between Santa Rosa in Sonoma County and San Rafael in Marin. SMART is currently working out details of an official groundbreaking ceremony, though preliminary work began last month.

Funding for the additional work, generated through a $191 million bond sale in December, was held in an escrow account pending the result of efforts to repeal the quarter-cent tax known as Measure Q. With the failure, SMART will initiate what Mr. Mansourian said is a two-to-three-month legal process to release the revenue.

RepealSMART, the group seeking to give voters the chance to repeal the tax, was 302 votes short of the minimum threshold that election officials said was necessary before advancing to the next step in the ballot process.

Voter registrars in both counties said they would verify the petitions only if they reached a combined 14,902. That’s the number proponents contended was necessary to put a repeal measure before voters in November, a threshold set by the state’s Prop. 218 and roughly 15 percent of residents in both counties. Officials from SMART argued that 39,000 signatures must be collected to call an election.

“This has been a cloud over our heads for a long time,” said Valerie Brown, chair of the SMART Board of Directors and Sonoma County supervisor. Ms. Brown said that the board valued the democratic process, “but now we can really get the wheels rolling.”

Election officials in Marin County counted 9,111 unverified signatures last Monday, joining the 5,471 that officials counted in Sonoma County on the previous Friday. Members of RepealSMART were collecting the signatures until hours before their Friday deadline, six months after filing their intent to petition in August of 2011.

Some of the signatures could have been thrown out in the verification process. Gloria Colter, assistant registrar of voters in Sonoma County, said that inspections can reveal problems like duplicate signatures, out-of-county voter registration and other issues.

Clay Mitchell, co-chair of RepealSMART, said he is among those who reversed their support of the tax after the economic downturn forced SMART to scale back plans to build the entire 70-mile system at once, from Coverdale in Sonoma County to Larkspur in Marin. SMART officials have given no specific timeline for when they will extend the initial segment, saying that they will wait for the economic climate to improve and consider a bus service in the meantime.

Voters should be given a chance to repeal the tax after those changes to the SMART project, Mr. Mitchell said. While RepealSMART enlisted the help of paid petitioners as the deadline approached, he said that their approximately 250 volunteers represented at least 90 percent of the effort.

Despite the failure of the measure, Mr. Mitchell said the results showed that an increasing number of people have come to question support of the proposed transit system after passing Measure Q with a 70-percent majority in 2008.

Mr. Mitchell said he and other repeal supporters believe that they weren’t given clear requirements during the petition process, delaying their efforts. Additionally, since the SMART board of directors would determine if the signatures were sufficient to call an election, the board was unlikely to support the lower threshold, he said.

Yet the SMART board’s vice chair and Marin Supervisor Judy Arnold, said that transparency-focused efforts like webcasted meetings and outreach had likely enhanced public support of the project.

 “I think being open and transparent with the public – that’s what they responded to in not signing the petition,” she said.

RepealSMART’s core members will be meeting soon to determine their future plans, according to Mr. Mitchell. Those plans could include filing a notice of intent to collect signatures for a new, identical ballot measure.

Despite speculation that the efforts of RepealSMART would lead to an unfavorable interest rate on the bonds, Mr. Mansourian said the $1.6 billion in offers it received allowed sellers to negotiate a rate of less than 1 percent. Depending on financial conditions, the bonds could either remain at a shorter-term multimodal bond rate or be converted to a longer-term fixed rate.

SMART’s board awarded a $103 million design-build contract for its first phase of construction early this month to railroad specialists Stacy and Witbeck Inc. and Herzog Contracting Corp. The work, expected to create 1,000 jobs, will entail many underlying elements of the system, including tracks, railroad crossings and bridges. It stops short of downtown San Rafael, were further complications will merit a separate contract.

The initial segment of the SMART system between Santa Rosa in Sonoma County and San Rafael in Marin is expected to be completed in 2015 or late 2016.