RICHMOND -- The City Council and top bureaucrats in this city have spoken in rare unanimity: Any northern extension of the BART lines must come through Richmond, and studying other options is a nonstarter.

"Any extension that doesn't go through Richmond is a dealbreaker," Councilman Jim Rogers said at Tuesday's council meeting. "It's dead on arrival politically."

Rogers and a unanimous council Tuesday declared that subsequent studies should focus on northern expansion through Richmond, not through the El Cerrito Del Norte station along the Interstate 80 corridor.

The finality of the language and the insistence on limiting the scope of study did not sit well with BART Director Zakhary Mallett, whose District 7 covers most of West Contra Costa. Mallet was visibly discomfited during Tuesday's meeting, particularly when Rogers added a friendly amendment to Councilman Tom Butt's resolution to not participate or fund any further studies that explore "turning Richmond into a spur" and extending from Del Norte.

Mallett was still dumbfounded one day later.

"I thought they would at least allow an objective study to take place," Mallett said. "I didn't even conceive of a decision not to study alternatives."

But for Richmond, there was no hesitation. The momentum on the Richmond-or-bust philosophy built speed in the past month when Richard Mitchell, the city's director of Planning and Building Services, wrote a letter to Contra Costa County Supervisor John Gioia, of Richmond.

The five-page memo, which was circulated among county supervisors and staff, unequivocally stated that Richmond is the superior extension point because of linkages with AC Transit and Amtrak and the city's size and projected growth rate.

Mitchell, who also sits on the Hercules Planning Commission, also wrote that extension from El Cerrito Del Norte, which already has more than twice the ridership of the Richmond station, would " ... effectively isolate and downgrade the downtown Richmond station."

Mallett said he was surprised by Mitchell's letter, which was replete with italicized and underlined statements.

"I expected such emotions to be exclaimed by politicians, as opposed to professional staff," Mallett said, adding that he saw Mitchell as the "driving force" behind the movement to quash a new study.

"(The city has) effectively stated that if there is no feasible alternative to the Richmond station, they would rather have no extension than a feasible extension that originates elsewhere," Mallett said. "I believe (it's) misrepresentative of the city's broader population because primary beneficiaries of any extension will be residents in Richmond's northern, northeast and eastern quadrants."

Richmond officials disagree, saying studies were done in the 1980s and '90s and that they think extending through the downtown station is best not just for their city but West County and the transit system.

Mitchell declined to answer when asked who authorized him to write the letter to the county. City Manager Bill Lindsay said in an email this week that he did not authorize Mitchell to write the memo but that "his comments were consistent with adopted City Council policy and, therefore, appropriate in my view."

Mallett noted that a study could be commissioned by other affected cities even if Richmond doesn't buy in.

"I'm mildly optimistic" about starting a study in the next year, he said.

Contact Robert Rogers at 510-262-2726 . Follow him at Twitter.com/roberthrogers.