San Francisco interim District Attorney Suzy Loftus announced Wednesday that she was pulling the plug on predecessor George Gascón’s program to divert first-time DUI cases, taking a direct shot at Chesa Boudin, her main challenger in the upcoming election.

Gascón quietly launched the program this year to cut down on the number of misdemeanor cases clogging court calendars at the Hall of Justice by sending low-level DUI cases to neighborhood courts.

In order to qualify, offenders had to have a blood alcohol content between 0.08% and 0.16%. Defendants in the diversion program would agree to undergo behavioral therapy in exchange for having the charge dismissed.

The decision to kill the program is Loftus’ first policy announcement since her controversial appointment by Mayor London Breed just weeks before the Nov. 5 election. Gascón resigned after nearly nine years in office to pursue a run for district attorney in Los Angeles County.

Boudin, an attorney in the public defender’s office, has run a campaign promising to divert first-time DUI cases similar to Gascón. During a debate Monday at UCSF, Boudin challenged Loftus on the issue after catching wind of the move.

“I think diversion programs are more humane, more cost-effective and, fundamentally, more consistent with an approach that uses prison and jail as a last resort,” he said.

Nancy Tung, an attorney in the Alameda County district attorney’s office who is also running, credited herself for Loftus’ policy change.

“I think it’s great Suzy is following my lead on this,” Tung said. “I’m the first person who has taken Chesa on in this idea. DUIs are some of the most important misdemeanors that we prosecute.”

Leif Dautch, a fourth candidate who is a deputy attorney general in California, agreed with killing the diversion program.

“Given the street safety crisis in San Francisco, and the fact that the average drunk driver will drive under the influence 80 times before their first arrest, I believe they should face strict criminal consequences the first time they are caught,” he said.

Loftus said Gascón’s pilot program has had the reverse of its intended effect. She said the number of DUI cases that went to trial increased by 10% over the short period when DUI cases were being diverted.

“Traffic safety is so important for all of us, particularly given that so many of us have lost a loved one due to someone driving under the influence,” Loftus said in a statement. “These deaths are preventable, and prevention starts with people knowing there is accountability when it comes to drinking and driving.”

Loftus said she ordered a review of current offers in DUI prosecutions “to ensure that prosecutions are handled efficiently.”

DUIs have the lowest recidivism rates of any crime at below 6%, according to the district attorney’s office.

“Our enforcement of our traffic laws and our DUI laws are working, so we shouldn’t change it,” Loftus said at Monday’s debate.

Max Szabo, a spokesman for Gascón, defended the diversion program.

“Misdemeanor DUIs are the bulk of the trial calendar,” he said. “They clog up the courts and delay adjudication of more serious cases, leading to extended jail stays at a time where the city is looking to close its jail.”

San Francisco has had 24 traffic fatalities this year.

Evan Sernoffsky is a San Francisco Chronicle staff writer. Email: esernoffsky@sfchronicle.com Twitter: @EvanSernoffsky