Oakland city officials say City Council President Rebecca Kaplan’s budget proposal is “too flawed to fix” and have strongly advised the council against adopting it — the latest showdown between the council president and the city administration.

City Administrator Sabrina Landreth said Kaplan’s proposal inflates revenue projections and, if adopted, could result in layoffs, a hiring freeze and a $58.7 million deficit for the city.

“You can’t just invent revenue,” Landreth said. “We would love to fund more things in our budget, but we have to have realistic revenue in order to support that. I’m very concerned that this appears to have almost $100 million of inflated revenue projections.”

Kaplan didn’t consult the city’s finance department when she drafted her budget proposal or provide it before going public, as required by city policy, and as a result the proposal has “numerous technical errors, misuses restricted funds, and violates various City and State laws,” Finance Director Katano Kasaine wrote in a response to the plan.

“I have a lot of experience working on budgets specifically in the city of Oakland, and there is probably nobody in this organization that knows Oakland’s budget better than I do,” Landreth said. “I can say for certain that if the council were to adopt this, this would have severe impacts on our ability to provide services to our community and maintain the organizational health that we have worked so hard to achieve.”

But Kaplan said she did send her proposal to the administration and the city’s financial analyst, but said “they chose not to” work with her.

Kaplan released her budget proposal last week, as required by city policy, in response to the $3.2 billion budget proposal the mayor released last month. The proposal drew concerns when Kaplan recommended cutting the city’s new Department of Transportation and firing its director, just as they start a $100 million effort to fix deteriorating roads and fill potholes. Some observers viewed the recommendation as an opportunity for Kaplan to undermine Mayor Libby Schaaf, a longtime political foe.

On Wednesday, Kaplan reversed her recommendation on the transportation department. Instead she asked for “oversight in assignment of roles and duties and reducing duplication” of job duties between OakDOT and the Public Works Department.

Kaplan made some changes to her proposal last week after Landreth pointed out violations to city budget policies. She said her projections aren’t inflated and the city always under-budgets the revenue.

“Their projections are low and have been consistently every year,” Kaplan said. “I’m also, I want to be clear, proposing new things to bring in revenue so it’s not just that they’re underestimating business tax and transient tax. But I’m also proposing to actually add new revenue strategies so it’s not just that I’m saying they’re off by some amount.”

Jim Ross, a political consultant who ran Kaplan’s campaign in 2014, said it’s not unusual for cities to under-project their revenue.

“One of the things that you want to do when you’re doing a budget is you want to make sure you’re setting expectations,” he said. “You would rather under-promise and over-deliver than over-promise and under-deliver.”

In her proposal, Kaplan allocates $4 million for wildfire prevention — also a priority for Schaaf — to come from a voter-approved measure, but doesn’t clarify what measure. Kaplan also noted $1.5 million in additional revenue from parking taxes and said that additional revenue is available because the city’s parking tax isn’t being applied to all off-street parking garages in the city.

Additionally, Kaplan said she plans to save

$1 million per year by reducing time spent by the Police Department transporting people to the Santa Rita Jail.

“I’m asking that we look at some policy around what are the offenses for which we do or don’t take people into custody for,” Kaplan said. “It should be for the serious violent ones. That then reduces the amount of time, money, excess overtime being spent schlepping people” to Santa Rita Jail.

Kaplan will present her proposal to the council on Monday. The administration will also present its analysis. The City Council will vote on the budget by June 30.

Sarah Ravani is a San Francisco Chronicle staff writer. Email: sravani@sfchronicle.com Twitter: @SarRavani