President Obama will unveil a proposal for a $302 billion, four-year transportation bill during a speech today in Minnesota, according to an announcement from the White House. A fact sheet from the administration indicates the proposal would increase dedicated funding for transit more than funding for highways.

The proposal would represent a 38 percent spending increase over the current $109 billion, 2-year law, known as MAP-21, and is the most concrete long-term transportation bill proposed by the Obama administration, which has never put forward a funding stream until now.

The $300 billion spending plan does not raise the gas tax. Instead, it calls for directing some $150 billion from “business tax reform” to help shore up the Highway Trust Fund, which is set to go broke late this summer. The White House has not released more information about how the funding stream would operate, but the press release calls it “one-time transition revenue,” so the idea seems to be that in four years, a different revenue stream would have to be identified.

The White House announcement said Obama’s proposal “will show how we can invest in the things we need to grow and create jobs by closing unfair tax loopholes, lowering tax rates, and making the system more fair.”

Such a funding method would represent a major break from relying on the gas tax to pay for the national transportation program. The gas tax hasn’t been raised in two decades, and inflation and rising fuel efficiency have eroded its value. In 2012, the federal gasoline tax brought in $35 billion, but the feds allocated $54 billion in transportation spending, with other sources, including general tax revenues, making up the difference.

Obama will also announce the upcoming $600 million round of funding for TIGER, US DOT’s popular competitive grant program for local transportation projects, which has already been approved by Congress. The program has funded $1 billion in city transit projects, nearly as much for intercity rail, and $153 million in biking and walking projects since it was introduced in 2009.

More details about the president’s “vision for a 21st century transportation infrastructure” will be available after the speech today in St. Paul, which will take place inside the city’s restored Union Depot train station.