Progress on a state transportation bill is moving a bit like traffic in Seattle’s rush hour. Proposals being considered by the Washington Legislature are bogged down by differences between Democrats who control the House and the governor’s chair, and Republicans who have the upper hand thanks to two Democrats who caucus with the GOP.

It appears to be a backup and not gridlock. Both sides agree on a phased-in gas tax increase, curiously higher in the Republican proposal: 11.5 cents per gallon in the Majority Coalition plan, 10.5 cents from the Democrats. The Senate’s plan would cost about $12 billion over 12 years, the House’s $10 billion. The two sides largely agree on projects that include widening Interstate 90 over Snoqualmie Pass, improving access to the ports of Seattle and Tacoma and widening Interstate 405 through the Seattle suburbs.

But fiscal reforms pose a major difference. The state imposes a sales tax on transportation projects, with the money going to the general fund; the Majority Coalition wants to return that money to transportation. Democrats claim that idea would erode funding for other state programs and are quick to cite the state Supreme Court’s mandate that the state adequately fund K-12 education.

Another clash concerns Model Toxics Control Act, approved by voters in 1989 to create a fund that cleans up hazardous waste sites. The Majority Coalition wants to shift money from that fund to stormwater improvements, but Democrats and their environmental allies want no part of it. Republicans also want to modify prevailing wage requirements, also something Democrats and their labor allies want left alone. The legislative bodies also are split over how highway-centric the package should be; urban legislators want more for transit and bicycle and pedestrian paths, which have strong constituencies in Central Puget Sound but less support among the Majority Coalition.

Amid all these differences, there is plenty of room to compromise. Democrats need to lend an ear to the need for reforms, while Republicans may need to widen their focus from highways to include other modes of transport. But while lawmakers are working that out, there are also other factors to consider.

Legislators up for re-election in 2014 will run with this vote as a campaign issue. And given the present political climate, any gas tax increase is fodder for a public vote, which is what happened the last time the Legislature went this route. In 2005, after lawmakers approved a 9.5-cent-per-gallon increase, an effort to repeal it failed 54.6 to 45.4 percent.

Recent polling has found softening opposition to gas tax hikes in the wake of last spring’s collapse of the Interstate 5 bridge over the Skagit River; a November Elway Poll found an almost evenly split state electorate, down from significant opposition from earlier in the year. A separate survey of 5,765 residents by the Washington State Transportation Commission found almost 80 percent of respondents want an emphasis on existing road maintenance and safety. There were also majorities in the survey who favored reducing congestion and expanding transit.

The best approach would be projects that carry the biggest benefit to the state’s economic vitality, which means those that enable the movement of goods across the state — especially through Snoqualmie Pass — and into westside ports. These are the projects that have the most impact on jobs statewide and would ensure a vibrant economy. Legislators also should note popular sentiment that our present road system needs maintenance and repairs.

In addition, lawmakers eventually must look at gas-tax alternatives. Improved auto fuel efficiency and a reduction in miles driven have eroded the gas tax’s effectiveness, and other states have recognized this and gone in different directions. Instead of a 17.5-cent gas tax, Virginia opted for a 3.5 percent wholesale tax paid by gas stations, an increase in registration fees and a separate fee for hybrid vehicles. Pennsylvania raised wholesale gas prices and increased the cost of driver’s licenses and traffic fines. In a number of states including Washington, there has been talk of a tax based on the number of miles driven, though no one has quite figured out how to implement it.

And lawmakers would have to prove that financial reforms are taking effect, and that the state’s transportation projects are being built efficiently. This includes oversight of the state Department of Transportation, which is still dealing with the public fallout of misaligned freeway off-ramps and floating-bridge pontoons that leak. The public must be assured that the agency will be held accountable.

Action may come this month in a special session, or next year in the regular session. And action is needed, especially to assure the movement of goods, but it must be done in a way that passes muster with a tax-leery public.

• Members of the Yakima Herald-Republic editorial board are Sharon J. Prill, Bob Crider, Frank Purdy and Karen Troianello.