The Sonoma-Marin Area Rail Transit District on Tuesday completed the sale of $191 million in construction bonds.

The bond sale comes one day after the district completed negotiations with a construction company that has emerged as the finalist among five bidders. On Jan. 9, SMART directors will consider awarding a contract to the company, which the agency would not identify, to build a piece of the rail line.

Both are major steps forward for SMART's effort to build the first segment of a commute rail line from Railroad Square in Santa Rosa to downtown San Rafael, with service likely to begin in 2015 or 2016.

"These are the times to build and these are the times to get the financing," General Manager Farhad Mansourian said.

The bond sale will provide almost half of the $360 million needed by SMART to build the first segment of the rail line. The remaining money for the segment would come from local, state and federal funds.

The bond sale to 14 purchasers was finalized Tuesday morning, at a variable interest rate of 0.2 to 0.8 percent, which can be converted later to fixed rates that are currently 4 to 4.5 percent, Mansourian said.

SMART began selling the construction bonds last week, but officials refused to acknowledge the sale or disclose the terms until Tuesday.

After expenses, the sale raised $171 million toward the cost of building a 37-mile commute rail line, with stations and necessary infrastructure, from downtown Santa Rosa to downtown San Rafael.

The money will be held in an escrow account until the fate of a campaign to overturn the SMART sales tax is decided. If the repeal effort fails, the money will be released to pay for construction. If the repeal effort succeeds, the money will be returned to bond purchasers.

SMART opponents were critical of the bond sale.

"It is a foolish move, wasteful spending of taxpayer dollars," said Clay Mitchell of Windsor, co-chairman of RepealSMART. "They won't be able to use the money after we submit the signatures at the end of January. It will push it out until November. They will be paying all that money until the issue gets resolved."

Even with the money in escrow, SMART still has enough cash on hand, $45 million, and funds from the other sources to award a construction contract now, Mansourian said.

The first contract would cover work from Santa Rosa to the Marin Civic Center. The estimated cost is $107 million.

Before details can be released, Mansourian said the contractor must complete insurance and bond requirements and there is an appeal period.

However, SMART officials have characterized the bids as favorable and said the district may be able to accomplish more work with the money than first proposed.

"There are additional things we can present to the public," said Mansourian, referring to the scope of work.