Rep. Paul Ryan’s budget proposal has gotten a conversation going about a tax code rewrite. Rep. Dave Camp, head of the Ways and Means Committee, recently put out a small business proposal that included some tax reform, and he’s pledged to pursue more reforms this year. His committee has already set up 11 bipartisan working groups to work on it. Sen. Max Baucus, chair of the Finance Committee, has expressed a similar readiness to tackle the issue.

The Washington Post’s Jerry Markon wrote what would appear to be an exhaustive article about all the interest groups lining up to lobby Congress on a tax code rewrite: Broadway producers, Native American tribes, roofers, and of course, the country’s biggest corporations. But transportation lobbyists aren’t even mentioned. It looks like a simple hike in the gas tax isn’t part of the tax reform conversation.

Democratic Capitol Hill staffers say it should be, in light of the convoluted funding mechanisms for the most recent transportation bill. “We always talk about wanting to do tax reform and we never do,” one told me this week. “We need to have that conversation. There are only so many fake pay-fors we can find.”

“It’s hard to raise the gas tax in the context of a transportation package,” said another. “The magnitude of the increase we need just to maintain what we have makes it hard.”

But tax reform might not be the place either. “I think tax reform is going to look more just at the income tax,” said Annette Nellen, professor of accounting and taxation at San Jose State University. “The gas tax is supposed to go into the Highway Trust Fund, so I don’t think it would come up, if there is an issue about needing revenue. The obstacle to the gas tax is just that [Congress is] concerned the public thinks the price of gas is already too high, even though the excise tax hasn’t been changed in some time.”

Nellen thinks Congress will probably be forced to bail out the trust fund a few more times before they’ll actually do anything about the gas tax.

What might happen in the context of tax reform this year, however, is an elimination of tax loopholes for the oil and gas industry. President Obama has been clear that that is a priority of his. Nellen says that could make a gas tax increase even less likely: Oil companies facing higher taxes could pass along the expense to consumers, raising the price of gas and making the public even less willing to pay more at the pump – or making Congress too scared to even ask.

A transportation-minded staffer could sneak a gas-tax increase into a tax reform bill, of course, but Nellen says the rewrite currently being teed up is being framed as an opportunity to simplify the tax code and eliminate complicated loopholes and rules. She says the gas tax is part of another discussion.

The good news, Nellen said, is that a gas tax increase is simple. It doesn’t actually need to be part of an overarching conversation about tax rewrites or even transportation policy. It’s a simple equation: adjust the excise tax on gasoline to make sure there’s sufficient money in the Highway Trust Fund. “That would be the logical way to deal with that,” Nellen said. “As far as tax reform, they’re talking about major changes to tax rules in the system. Unless you’re talking about moving to a vehicle-miles approach, I wouldn’t put just increasing the dollar amount of the current excise tax under tax reform.”

She makes it sound so straightforward, doesn’t she?

The fact is, we don’t need to search for the perfect legislative vehicle to raise the gas tax. We just need the political will.