An overwhelming majority of Americans favor government action to reduce drug prices, but that policy may not be included in the final bill. Tax increases on the wealthy are also very popular, but it is unclear how many of them will make it, either. The same goes for a proposed expansion of Medicare to include dental, hearing and vision coverage.

It is even possible that the entire bill — which would expand pre-K, community college, Medicare, Medicaid, paid family leave, child tax credits, clean-energy programs and more, while significantly increasing taxes on people making more than $400,000 — will fail. Yet polls have consistently showed it to be popular, more so than some past Democratic priorities, like Bill Clinton’s or Barack Obama’s health care bills. And if this bill fails, Democrats are likely to enter next year’s midterm congressional elections looking divided and unable to govern.

It’s still too early to be sure about any of this. Democratic leaders may find a way to keep their party unified enough to pass a major bill, despite their narrow control of Congress. If that happens, the squabbling of recent weeks may not matter much.

But the Democratic tensions are real. This morning, we’ll explain the two big reasons that the party is struggling to pass a bill that most voters favor.