SAN JOSE — South Bay BART riders can expect to wait well into next year for the opening of new stations in Milpitas and North San Jose that were supposed to make their debuts this month.

After confirming in November that the new stations won’t open in 2019 after all, nobody at BART or the Santa Clara Valley Transportation Authority, which built the long-awaited $2.3 billion extension, has been willing to say precisely when in 2020 passengers will finally be able to ride to San Jose.

But estimates laid out by the agencies in recent weeks indicate the Milpitas and Berryessa stations might not open until April — if not later.

Before the stations can open, VTA crews need to finish their work on the 10-mile extension and resolve problems BART workers identified when they worked on the system earlier this fall. VTA spokeswoman Bernice Alaniz said the agency plans to wrap up its work by Jan. 31.

From there, BART will need a while to conduct its own safety testing and make sure there aren’t any lingering problems that it still wants VTA to fix. Precisely how long that will take isn’t clear.

BART Assistant Chief Engineer Shane Edwards told the transit agency’s board at a meeting last month that crews would need 12 weeks to do the work. Edwards’ estimate would put the opening around the final weekend of April, though he cautioned that “there is not a hard date at this time.”

On Thursday, BART spokesman Jim Allison backed away from that timeline, saying the agency’s leaders are no longer hazarding a guess about when the stations will open. And Allison did not give any indication that people anxiously awaiting the start of BART service in Santa Clara County should expect it any sooner.

“We aren’t going to publicly state a number of weeks we will need for testing because, at this point, there are too many variables,” Allison said. “Bottom line is that the extension will be ready for revenue service as soon as it is safe and reliable.”

The extension to the new Milpitas and Berryessa stations is the first phase of a project that will eventually bring BART through downtown San Jose and into Santa Clara. When construction on the extension began, the first two stations were supposed to open in 2016.

The project has been hampered by a series of delays and missed deadlines, pushing the planned opening to Dec. 28, 2019. As that date approached, crews from both agencies scrambled to resolve a mounting list of problems as VTA and BART officials insisted the stations would open before the end of the year.

In mid-November, VTA quietly acknowledged that would not happen.

Supervisor Cindy Chavez, who was elected chair of the VTA board Thursday night, stressed that the testing work that still needs to be done on the extension is vital to ensure the system is safe.

“I recognize that the voters have voted to support BART, and they deserve to have access to it as soon as possible,” Chavez said. “I’m anxious for it to be open.”

But, Chavez added, “Right now I’m just focused on it being done right, and well.”

Meanwhile VTA is moving forward with a planned slate of service changes that will go into effect Dec. 28. The new service is good news for some VTA riders and bad news for others — it calls for more frequent service along 19 of the system’s more popular routes, while also reducing frequency on less-popular lines and eliminating 17 routes entirely.

Among the cuts are three express bus lines and the Almaden light rail spur, which includes two stations. Another VTA spokeswoman, Brandi Childress, said some of the discontinued routes are being consolidated with others, and stressed that VTA’s total service hours will stay the same.

As commuters wait for the new BART stations to open, VTA will continue to run one of its express bus routes to the Warm Springs station but will eliminate the other.

Route 181, which connects BART riders to stops in San Jose, will keep running until the new stations open, with the addition of a stop at VTA’s Milpitas light rail station. The extra stop is expected to add about five minutes to the trip, Childress said. Route 180, between Warm Springs and Milpitas’ Great Mall is being shut down on Dec. 28. That route which will eventually be served by a new BART station.

Some riders have complained that shutting down routes will only worsen VTA’s declining ridership and budget woes. While Chavez said she hopes the more frequent service along core routes will make VTA’s service more attractive to potential riders, she also said Santa Clara County ought to be putting its money toward an expanded public transportation system that serves more people.

Cutting lines, Chavez said, “Is the wrong direction.”