The 19-page plan to be proposed by Democrats includes $329 billion for investment in transportation systems, including improving safety measures for bicyclists and pedestrians, and $105 billion for transit agencies and maintenance needs. The framework also includes $55 billion in railway investments for both the expansion of the country’s passenger rail network and improvement of Amtrak stations and services, $19.7 billion for the upkeep of harbors and ports, $86 billion for the expansion of broadband access and additional funds to address greenhouse gas pollution and increase climate resiliency.

There will also be $21.4 billion for the preservation of clean drinking water and communities dealing with toxic chemicals that can contaminate drinking water, known as PFAS. Democrats struggled to include stronger regulations for PFAS in must-pass defense policy legislation late last year, and passed a stand-alone measure in early January.

And while the framework also includes transportation and infrastructure legislation routinely addressed by Congress, Democrats made a point of emphasizing efforts to counter climate change and its effects.

An infrastructure plan has been an elusive goal for both the Trump administration and Congress over the last three years. The phrase “Infrastructure Week” has become something of a joke that encapsulates the dysfunction of Washington in the Trump era, after the White House repeatedly scheduled one during Mr. Trump’s first two years in office, only to have it overshadowed by a jarring comment by the president or a damaging revelation about him.

Nine months before Election Day, a $1 trillion infrastructure plan is still one of Mr. Trump’s unfulfilled promises from his inaugural campaign.

The Senate has begun work on its own infrastructure legislation, with one highway bill passing unanimously out of the Senate Environment and Public Works Committee this session. That bill authorizes $287 billion over five years, and includes provisions for road safety and programs to maintain and repair roads and bridges.

The template to be announced on Wednesday is the first significant overture by Democrats on the issue since the blowup at the White House in May, when the president said he would not strike a compromise on infrastructure while Democrats were working to investigate him.