The 10-year plan would boost gasoline excise taxes by 12 cents a gallon - a 43 percent increase.
The plan also includes a sliding fee on vehicles, with owners of cheaper vehicles paying less.
For the first time, owners of zero emission vehicles would pay a $100 annual fee, since they use public roads but don't pay gasoline taxes.
The gas tax increase would be the largest in state history and would increase over time, Assembly and Senate Republicans said in opposing the plan.
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"Yes, it costs money. And if the roof in your house is leaking, you better fix it, because it gets worse all the time," Gov. Jerry Brown said at a Capitol news conference. "This is mostly about fixing what we already have. If for some reason people try to fight this, and God help us if they were successful, they won't defeat this, they'll just delay it and make the expenses go up."
The proposal includes a constitutional amendment requiring that the money be spent only on transportation projects, and it would create an inspector general to make sure money isn't misspent.
Critics have long complained that money raised by transportation taxes has been siphoned off for other uses, something the constitutional amendment is designed to prevent. Republican lawmakers renewed that objection in a joint statement arguing that California already collects enough money if only it is spent on the right projects.
"Californians already pay some of the highest gas taxes in the nation," Republican lawmakers said in a joint statement, calling the Democrats' proposal a "costly and burdensome plan that forces ordinary Californians to bail out Sacramento for years of neglecting our roads."
The Democratic governor has said California has $59 billion in deferred maintenance on state highways and $78 billion on local streets and roads. Last month he suggested tax increases may be required to address the problem.
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He has set an April 6 goal for the Legislature to pass a transportation funding package.
Brown, Senate Pro Tem Kevin de Leon and Assembly Speaker Anthony Rendon were set to unveil the package at the Capitol.
It's the third time Brown has attempted to address the multibillion-dollar backlog in transportation repairs and upgrades through tax increases. Brown's previous plans and others calling for tax increases have repeatedly stalled in the Legislature, with Republicans and moderate Democrats reluctant to back the higher taxes.
Democrats control enough seats for the proposal to pass the Assembly and Senate with the two-thirds majority required for tax increases. Brown will need nearly all of them unless he can pick up support from Republicans, who have opposed raising taxes to pay for road construction.
The Assembly will be particularly challenging. A number of Democrats eked out wins in the November election and could be vulnerable in the next campaign if they vote to raise taxes. Moderate Democrats, many from inland districts where voters are generally poorer and face long commutes to work, may be concerned about raising gas prices.
"We can no longer afford to ignore our crumbling and limited public transportation infrastructure," Sen. Scott Wiener, a Democrat from San Francisco, said in a statement. He praised the agreement for increasing money for public transportation, but said public transit needs even more money.
In the new proposal:
- The gasoline tax would raise $24.4 billion over 10 years.
- The state's current 16-cent-a-gallon diesel excise tax would climb by 20 cents - a 125 percent increase. It would raise $7.3 billion over 10 years.
- An increase in the diesel sales tax would raise $3.5 billion over 10 years.
- The sliding vehicle fee is similar to what owners already pay annually to the state Department of Motor Vehicles. It is projected to raise $16.3 billion.
- The $100 annual fee on zero emission vehicles would start in 2020 and raise $200 million.