Wall Street's hopefuls might be misreading Washington's realities.

Expectations that President Donald Trump will push through an investor-friendly fiscal stimulus package have helped boost equity markets to multiyear highs.

Even a congressional address by the president that was light on details last week couldn't prevent the Dow Jones Industrial Average sailing past 21,000.

But a new note from Goldman Sachs Group Inc. economists suggests investors are misinterpreting the political timeline, and with it the market tea leaves.

Led by Alec Phillips, the bank's senior U.S. political economist, the strategists predict that President Trump will be tied up with repealing the Affordable Care Act (ACA) known as Obamacare this fiscal year, leaving little room for tax reform and infrastructure spending.

Goldman's timeline (above) shows when the bank predicts these proposals will turn into some sort of policy action. The ACA will be a big focus until this summer, and tax reform could drag out into 2018. Infrastructure, meanwhile, doesn't even hit DC's radar until next year.

"In our view, the slow process on ACA repeal signals that tax reform is likely to take longer than initially expected and that the final tax legislation that Congress enacts is likely to be less radical," Phillips and his team wrote in a note published on Friday, echoing comments made last month.

Infrastructure spending is "still on the agenda, but for now remains an afterthought," the economists added. "Our expectation is that new infrastructure funding will be enacted this year or next, but that it is likely to take the form of tax incentives that might be included in tax reform legislation."