President Trump and congressional Republicans are expected to make the country’s infrastructure (think airports, bridges, cellphone towers, public schools and roads) one of their major legislative priorities this year. It’s a big opportunity for Republicans — particularly the president. But I’m pretty sure they’re not going to be able to take advantage of it.

Let me start by explaining the opportunity. Republicans’ two most important legislative proposals last year — taxes and health care — were opposed almost universally by congressional Democrats, disdained by policy experts, and disliked by most of the public. Polls suggest that even GOP voters were not very enthusiastic about the health care proposal. So Republicans basically spent all of 2017 on legislation that will do little to help them politically.

But infrastructure could be different — bipartisan, popular with the public and good politics for the GOP and Trump. Why?

First — on infrastructure policy, Trump and congressional Republicans aren’t as boxed in by existing GOP orthodoxy, so they have more freedom to write a bill that is popular with the public and sellable to Democrats. Republican members of Congress, particularly in the House, basically coalesced behind proposals on taxes and health care in the summer of 2016 — back when few people thought Trump had a chance of winning the White House. These proposals represented long-held views of top GOP lawmakers like House Speaker Paul Ryan and key interest groups in the party: that Obamacare should be repealed and corporate taxes cut.

Once Trump got into office, congressional Republicans stuck with those concepts, leaving the administration largely endorsing the GOP’s existing proposals, rather than shaping them.

But the congressional GOP agenda from the 2016 campaign did not include an infrastructure plan. That means Republicans can write a bill basically from scratch — one aimed at winning popular support. This is a particularly important opportunity for the president. Trump, who has largely governed like a traditional small-government and anti-regulation Republican, could use infrastructure to go back to the kind of populist conservatism he espoused during his campaign, with an FDR-style proposal to rebuild America.

More broadly, the two parties are not as entrenched in their views on infrastructure as they were on, say, health care, where Republicans were committed to repealing Obamacare and Democrats to defending it.

Second — for the bill to pass the Senate, it needs to get some Democratic votes, which means congressional Republicans and Trump can write a more moderate bill. Last year, on both taxes and health care, Republicans relied on budget reconciliation, a procedural move that allows some bills to pass with only 50 votes in the Senate, instead of the 60 usually required to ensure that a filibuster could be broken. By doing this, Republicans invested in passing these bills with only GOP votes, and they concentrated on wooing nearly every Republican member, even the most conservative, while basically ignoring congressional Democrats

But reconciliation can generally only be used for bills that make changes to long-term budgetary or fiscal policy. So an infrastructure bill, unless it was constructed in a very unusual way, could not be approved through reconciliation.

That may sound like a problem, but it could be a blessing in disguise for Trump and Republicans. There are 51 GOP senators, so the Republicans must write a bill that would appeal to at least nine Senate Democrats (to get to the required 60). Or, they must write one that is popular enough with the public that at least nine Senate Democrats would feel pressured to support it. GOP leaders and Trump could then explain away a bill that is not as conservative as some party activists and the party’s most conservative members would like by saying that it had to be bipartisan (and have some Democratic ideas) in order to pass.

So imagine that Republicans come up with a bipartisan infrastructure bill that is popular with the public and it passes. That could lift Trump’s job approval ratings, particularly with voters who describe themselves as independents, and therefore improve Republican chances of keeping control of the House and Senate in the midterm elections. And a bipartisan success on infrastructure could position Trump for other moves that would recast him as a centrist, deal-making president not completely wedded to the GOP — in short, a return to his brand from the 2016 campaign.

OK, yes, I admit: The scenario I laid out above sounds like I slept through 2017 and missed how Trump governed from the right and the two parties disagreed on everything. Don’t worry — I was there.

Here’s what is more likely to happen: Republicans will come up with an infrastructure proposal opposed by nearly all Democrats and some very conservative House Republicans, and it will struggle to pass. Why?

For one, the GOP appears to have settled on an infrastructure vision that Democrats probably won’t like. Last year, Senate Democrats proposed sending $1 trillion to states and cities over 10 years for projects like road building and improvements, funded by increasing taxes on both wealthy people and corporations.

Republicans say they have a $1 trillion infrastructure plan, too. But they are coalescing around a plan that would provide $200 billion to localities over 10 years — much less than the Democratic proposal. White House officials are hoping that those federal dollars inspire public-private partnerships and that eventually cities, states and businesses put up about $800 billion. Democrats say that states and cities don’t have enough money for that kind of spending.

Why would Republicans be headed in this direction? It’s hard to tell whether 1. Trump is more of a traditional conservative than his 2016 campaign suggested; 2. His advisers write his proposals, and they don’t really care about his populist rhetoric from the campaign trail; or 3. Trump and GOP leaders know they will eventually need Democratic votes but want to get congressional Republicans on board first, and a smaller, private sector-driven infrastructure bill is the best way to do that.

No. 3 is probably what is driving Republicans on infrastructure: the need to maintain party unity. But I think that Trump, even with this relatively conservative vision of infrastructure, will have trouble getting Republicans behind the proposal, particularly in the House. The promise of infrastructure legislation is that it will create jobs. But conservative House Republicans generally oppose more government spending and intervention to help the economy. Moreover, unemployment is very low right now, something that Republicans, including the president, are constantly touting. And Republicans just passed a big bill, the tax legislation, that they say will create even more jobs. So I expect many congressional Republicans, seeing no reason to vote for this infrastructure bill, will be looking for a way to kill it while not irritating Trump.

Second, the political environment is so toxic that it’s not clear that Democrats will work with the GOP and Trump even if Republicans write a bill that has some liberal ideas. The Democratic base is unified against Trump, and Democratic lawmakers on Capitol Hill — even those from more conservative-leaning states — were frustrated that the president and Republicans did not include them in governing for much of 2017. So it is difficult to see Democrats joining Trump and congressional Republicans to pass anything now.

Indeed, Democrats have strong incentives, in an election year, to block any Republican achievements and cast the GOP as a party that had total control of Washington for two years but did little beyond passing a tax cut that disproportionately benefited the wealthy. Also, Trump is so unpopular with voters that his backing a bill (on any issue) may decrease its chances of gaining popular support — no matter what is in the legislation.

One of the great questions of Trump’s tenure is what would have happened if he had started his administration with a bipartisan, populist infrastructure proposal instead of restrictions on travel from several predominantly Muslim countries, Obamacare repeal and other policies that galvanized liberal activists. But he didn’t, and I think Washington is now trapped in a dynamic in which Democrats are looking to oppose Trump’s initiatives and Trump and Republicans are writing proposals that reflect conservative views, rather than attempting to make bipartisan deals.

To reset this dynamic would take a major shift in strategy by Trump. Infrastructure reform seems like an opportunity for that kind of shift. But that would require a process in which members from both parties were collaborating on a bill that would truly have bipartisan support. Based on how Trump governed in 2017 and his current ideas on infrastructure, it’s very difficult to see that happening now.