It is once again Infrastructure Week in Washington, and this time, it might be more than a joke. Congressional Democratic leaders visited the White House on Tuesday to sketch out the contours of a bill, and initial reactions suggested that the meeting went well, with all principals minding their manners. The two sides will aim for a $2 trillion package targeted at rebuilding “roads, highways, bridges, tunnels and railroads, modernizing our air travel system, and expanding broadband access for our great farmers and rural America,” per a White House statement. Democrats and the Trump administration agreed to meet again in a few weeks to discuss the more nettlesome question of financing.

Is there any reason to believe that this infrastructure effort will end differently than any of the other times over the past decade that leaders have called for upgrading “our crumbling roads and bridges,” before forgetting about it? In fact, maybe. Some favorable incentives to pass such a bill are in place for the two most crucial figures in any major bipartisan legislation, House Speaker Nancy Pelosi and President Donald Trump. But there are still vast policy disagreements separating the two sides, and whether they allow those disagreements to scuttle the entire effort is a political choice that all involved will have to make.

Pelosi wants to show that her majority is capable of governing and to give her dozens of vulnerable House members—all of whom campaigned on passing an infrastructure bill—an accomplishment on which to run. Both she and those vulnerable members are particularly sensitive to the impression that they would only use their majority to investigate the president. This meeting, which Democrats requested just as they were getting a tsunami of questions about impeachment, was itself an effort to change the conversation.

In Trump’s case, he, too, would like a big, bipartisan accomplishment that throws trillions of dollars toward American jobs while he’s running for reelection. No longer does he have to abide by former adviser Gary Cohn’s plan from early 2018 to leverage a more modest investment of $200 billion through the private sector. (Trump never liked that plan and was so bored upon its presentation that he drew doodles about Steve Bannon throughout the meeting about it.) Democrats control the House now, and they would prefer to spend on public investment rather than give private corporations some money to pocket.

But, while the political will to spend trillions on infrastructure exists among both House Democrats and the White House, members of both parties are already drawing policy lines in the sand.

On Monday, Pelosi and Senate Democratic Leader Chuck Schumer sent a letter to the White House saying that the package must be paid for “with substantial, new and real revenue.” Schumer, speaking on the Senate floor later that day, offered a suggestion for a source of revenue: rolling back some of Republicans’ signature 2017 tax legislation.

“By reversing only the most egregious giveaways in President Trump’s tax bill—those given to the wealthiest of the wealthiest—and raising the corporate tax rate a smidge,” Schumer said. “We could finance the entirety of a trillion dollar infrastructure bill.” (Now that they’re looking at a $2 trillion bill, two smidges might be in order.) And while the president has been receptive to increasing the gas tax to pay for an infrastructure package, Democratic leaders are not.

“Unless President Trump considers undoing some of the 2017 tax cuts for the wealthy,” a source close to Schumer said, “Schumer won’t even consider a proposal from the president to raise the gas tax, of which the poor and working people would bear the brunt.”

“Working people shouldn’t take another big financial hit in order to be able to get to work and take care of essentials,” Sen. Ron Wyden, the ranking Democratic member of the Senate Finance Committee who was also at Tuesday’s White House meeting, told reporters on Monday, “and particularly not when the big multinational companies, which are causing most of the wear and tear to the infrastructure, got all of these tax breaks.”

I asked Wyden whether he had any reason to believe that the president would be open to undoing some of his biggest legislative accomplishment.

“You would have to ask him,” he said.

Or I wouldn’t, because such a bill would never reach the Oval Office. Senate Majority Leader Mitch McConnell said Tuesday that rolling back the 2017 tax bill, at all, to pay for an infrastructure package would be a “nonstarter” in the Senate.

“You would have to ask him,” Wyden said. Or I wouldn’t, because such a bill would never reach the Oval Office.

“This tax bill is what’s generated this robust economy,” McConnell said at his weekly press conference. “The last thing we want to do is step on all of this growth by stepping back and repealing, in effect, what has generated all of this prosperity and low unemployment.”

Republicans in Congress, along with some of the president’s advisers, would prefer to bring down the bill’s cost by loosening requisite environmental, permitting, and labor regulations. While Trump was meeting with Democrats, his chief of staff, Mick Mulvaney, made these points in an interview, saying that he’s told the president he “won’t see a single lane of traffic or road paved before the end of your second term” without regulatory changes.” Mulvaney was generally skeptical of a deal coming together.

“Do I think there’s an interest in doing it? Yes,” he said. “Do I think there’s probably more interest, especially on the Democrats’ part, to make a show for trying to get a deal? Yeah.”

Mick Mulvaney, a piece of work though he may be, may have it right here, even if it’s more of a two-way street than he lets on. As much as Pelosi may want to protect her front-line members facing reelection, she and Schumer must also recognize that cutting such a deal with Donald Trump would help his reelection chances and invite blowback from the Democratic base.

And congressional Republicans, too, don’t want to give off the impression that everything runs smoothly when the Republican president works with a Democratic Congress. The safer route for either side would be to set up the meetings, walk through the motions, blame the other party’s rigidity as the talks fall apart, and then campaign blandly on infrastructure ahead of the election. And if neither party wins unified control of Congress and the White House in 2020? Repeat.