The energy within the Democratic base lies with issues including Medicare-for-all, abolishing Immigration and Customs Enforcement, and holding the Trump administration accountable. But if you ask House Democrats what they want to make their first big agenda item if they win in 2018, they’re hoping it will finally be infrastructure week.

Vox recently talked to several Democratic lawmakers who mentioned one of their first major policy proposals will likely be a large infrastructure package focused on rebuilding roads and bridges, updating aging water pipes, and installing rural broadband. They want to focus on a bipartisan policy item that President Donald Trump has signaled he also wants to get done.

“Skills training and infrastructure need to be our initial focus,” said House Minority Whip Steny Hoyer, adding he’s recommended that move to the Democratic caucus and ranking members of committees. “I expect them to move bills on that, and my hope, my belief is, and my recommendation is that we move on these economic issues at the very beginning of the next Congress.”

And it’s not just moderates — an “Invest in America” proposal topped the recently released Congressional Progressive Caucus’s People’s Budget — a draft of the progressive flank’s wish list for 2019 and beyond.

“Infrastructure, I think would be fair to say, has a pretty broad consensus in our party,” Hoyer said in a recent interview with Vox. Hoyer added there’s a “sense that we need to bring that to the fore early on when we’re in charge ... focus on growing the economy.”

Plus — it’s something that House Republicans also want to get done. Rep. Bill Shuster (R-PA), the chair of the House Transportation and Infrastructure Committee, released a draft infrastructure bill a few weeks ago, calling for trillions of dollars to be invested in “projects of national significance” — relating to the nation’s highways and other transit.

It’s tempting to see this as one of the rare cross-partisan issues that Republicans and Democrats can actually agree on. But nothing is easy in Trump’s Washington. Some Democrats worry the move might seem too conciliatory to Republicans at a time when they want to set up clear distinctions between the two parties ahead of 2020. And most of all, it will matter if they can get Trump on board.

Republicans stalled on infrastructure this year. Can Democrats do better?

Even though infrastructure should be a winning issue in an election year, Republicans and the Trump administration haven’t been able to get much momentum going behind it. Shuster put out his recent proposal to generate discussion, but he’s under no illusions a plan will actually get done before November.

“It doesn’t appear anyone is interested in tackling infrastructure right now as we get closer to the election, which is unfortunate we didn’t do it earlier this year or late last year,” said Shuster, who added he expected his bill to get “mixed reviews” from his Republican colleagues.

There’s a lot in the Shuster bill that conservatives won’t support.

“I really like the chairman, but there is zero chance that the chairman’s plan gets anything other than a bit of discussion, both pro and con,” said Rep. Mark Meadows (R-NC), the chair of the conservative House Freedom Caucus and a member of the infrastructure committee. “There’s a whole lot that I don’t support in it.”

But the longer Republicans wait, the more likely that infrastructure vision could be shaped by Democrats in 2019.

Both Hoyer and the Congressional Progressive Caucus laid out what that future might look like in separate events this week. Both proposals hit on the same on the same goals — fixing ailing roads and bridges, updating aging water infrastructure like the lead pipes that poisoned the water in Flint, Michigan, and many other municipalities.

The Congressional Progressive Caucus wants the federal government to invest $2 trillion on infrastructure projects — including $100 billion allocated to expanding rural broadband access.

The fight will come down to how to pay for all of this

The federal gas tax is the key to financing massive new infrastructure projects, but the big fight always comes down to how much to raise it.

As Vox’s Matt Yglesias wrote:

Federal transportation infrastructure in the United States is primarily financed by the gasoline tax that was set at 18.4 cents per gallon in 1993. Over time, 25 years of inflation and steadily increasing fuel efficiency has ensured that the real per capita value of that funding stream has fallen.

“One of the tough things to do will to be to come to grips for how do we pay for this,” Hoyer said.

Shuster, for one, is proposing increasing the gas tax, including a 15-cent-per-gallon gasoline tax, a 20-cent-per-gallon diesel tax, plus additional taxes on things like bike tires and electric batteries for cars.

Shuster’s gas tax proposal is what drew rebukes from some conservatives. Even though Shuster isn’t proposing as drastic a raise (it’s actually less than the 25-cent-per-gallon increase that President Trump floated in February), some conservatives have also balked at the other tax proposals in the current plan, particularly one on bicycle tires.

The president ran on fixing America’s infrastructure in 2016, but since then, he’s shown little interest in the issue. The Trump administration’s lone infrastructure proposal called for $200 billion to be cut from the federal budget and moved to infrastructure projects, and asked states and local municipalities to pay the lion’s share.

As Yglesias wrote:

Right now, federally funded highways (that’s interstates and other routes) are financed on the basis of an 80-20 federal-state split, and federally funded mass transit projects usually get a 50-50 split. Trump’s proposal is to flip the 80-20 formula on its head and require that states and cities kick in at least $4 for every $1 in federal money they receive. This vision of a stingier matching formula is defensible — some experts feel that the current formula leads to over-investment in new highway projects with little transportation value — but the White House’s notion that it will lead to an actual surge in state and local infrastructure spending is difficult to support.

“I want you to imagine for just a second what the federal highway system would look like if it had been a 20 federal and 80 local contribution,” Hoyer scoffed at a recent press conference. “His infrastructure program that he proposed is woefully, woefully, woefully inadequate, and has been dismissed essentially, by his own colleagues in the Congress. I haven’t seen reasonable proposals, and none are being taken up by the Republicans in the House of Representatives.”

Democrats haven’t floated specific proposals for paying for their infrastructure wish list yet. But with 2018 poll numbers still looking good for Democrats, Trump may have to contend with the Democratic vision for infrastructure, rather than the one proposed by members of his own party.