SAN FRANCISCO (CBS SF) — One of San Francisco’s biggest political power brokers is threatening to blockade City Hall with thousands of vehicles if officials try to make busy Stockton Street a pedestrian-only area.

For the past year, the idea of making the annual pedestrian Winter Walk on Stockton Street into a year round affair appeared to be picking up steam at every turn.

“A lot of the merchants, a lot of the pedestrian activists and bike advocates are all saying this is something that would work,” said Paul Rose with the Municipal Transportation Agency.

The proposal has found a serious opponent: five feet of pure political power known as Rose Pak. She and her Chinatown allies has helped make and break every San Francisco mayor for the past 30 years.

Power broker Pak is fighting to keep the Stockton Street open to cars.

“We have about 300 family associations, district associations, temples, churches,” said Pak. “Everybody is here. 100 percent of our businesses rely on delivery trucks. Look at Chinatown any hour. You can’t move.”

Ironically, the Central Subway — the billion dollar plus construction project currently snarling Union Square with traffic — is meant to get cars and trucks off the street.

That is just what the walkway would do.

“It’s a more inviting atmosphere,” said Karin Flood of the Union Square Business District. “People feel safe. It’s exciting.”

For Pak, it’s about business as well.

“We have 54 empty store fronts,” she said.

Supporters counter that the plan at deserves a city-wide say.

“Let other groups and other neighborhoods weigh in,” said Flood.

But Pak says she wont budge from her position against the pedestrian walkway concept for Stockton Street.

“I don’t think traffic stoppage is open for negotiation,” stated Pak.

On Monday, she unveiled her plan to fight the Stockton Street proposal.

“Wait until I have my blockade of the MTA for a week and see how they like it,” said Pak. “We’ll have thousands of trucks and cars blockading the whole City Hall and MTA area for one week and see how they like it when no one can get in and out.”

Pak told CBS SF reporter Phil Matier she was completely serious about using her influence to make the blockade happen.

“And that’s a promise, not a threat,” said Pak. “That’s a reality.”