President Trump and congressional Democrats have a deal to figure out a plan to spend $2 trillion on new infrastructure for the country. Consider us skeptical that this will amount to anything tangible.

That’s in large part because Trump has proven to be an extremely unreliable negotiator, unwilling to make decisions that upset his base.

Both parties recognize the need to revitalize the nation’s roads, bridges and public transportation. But how to pay for it breaks down along partisan lines. Republicans don’t want to spend trillions in taxpayer money on this — which could mean either raising taxes or further increasing the deficit on their watch. Democrats are wary of any funding mechanism that could be seen as a handout to corporations, like private investment or giving tax breaks to developers to build roads.

“We want to hear his ideas on funding,” Senate Minority Leader Charles E. Schumer (D-N.Y.) told reporters after the Democrats’ meeting with Trump on Tuesday, calling that point “crucial.”

For now, Trump seems open to negotiating with Democrats on how to pay for this. Even agreeing to spend $2 trillion, in some form, is more in line with Democratic principles of big governance than Republican ones.

But “Chuck and Nancy,” as Trump likes to call the Senate and House Democratic leaders, respectively, have been burned before by deals with him. On guns, on immigration, on spending, Trump has offered policies that Democrats want, only to pull those back when he realizes his base thinks it’s a bad idea. Then he lurches to the right, and it’s as if the negotiations with Democrats had never happened.

After the high school shooting last year in Parkland, Fla., Trump sat in a meeting with congressional leaders and, with the news cameras broadcasting live, suggested banning assault weapons. It was a top priority for gun-control advocates, and Democrats were giddy that the president supported it.

“I am sure many of you in this room and many Americans around the country watched the president’s meeting on gun violence yesterday,” Schumer said, “and were rather stunned and surprised. Many of us pleasantly."

But as the traditional battle lines on guns made themselves clear, Trump quickly took his offers off the table, offering instead a plan to arm teachers in schools — a top priority for the National Rifle Association.

A similar story played out a few months earlier when Congress was trying to come up with an immigration deal to protect “dreamers” from deportation. Democrats thought they had a deal with Trump. Schumer and House Speaker Nancy Pelosi (D-Calif.) were so excited that they emerged from a dinner with him to announce in a joint statement they found a way to protect dreamers that did not include funding Trump’s border wall.

It was huge news. But the very next morning, Trump said no deal had been struck. He ended up putting together a proposal so far to the right that mainstream Republicans in Congress didn’t want to touch it.

As I wrote then: “When it comes time for the White House to put its own ideas in writing, he’ll land to the right of most of Washington, no matter how he seemed to be at the center or left just a few days before."

This infrastructure plan has a few things going for it that those other issues didn’t. Infrastructure isn’t nearly as much of a hot-button issue as guns and immigration are, so both sides may be more willing to make compromises without risking upsetting their base.

And Trump is entering a campaign season where he would like to, well, have something to campaign on from this Congress. (His other major legislative accomplishment, a new tax law, happened when Republicans were in control and doesn't seem to have been the political boon to Republicans that they hoped it would be.)

But any sort of bipartisan deal is an uphill battle. That’s true for any divided government and it’s doubly true because Trump, to date, has never followed through on a high-profile legislative deal with Democrats. We’ll believe it when we see it.