President Joe Biden’s plan for trillions of dollars in proposed spending and tax increases is entering a procedural and political thicket in Congress that’s likely to take at least until September to clear.

If all goes according to plan for Biden and Senate Majority Leader Chuck Schumer, the Senate would pass a bipartisan infrastructure deal next month as well as a budget blueprint that sets up a vote later on a far larger bill with trillions in social spending paid for in large part by tax hikes on the wealthy and corporations.

The budget bill could be passed with only Democratic votes in the Senate. But progressive Democrats in the House and Senate say they may not back an infrastructure package that includes concessions to Republicans without a guarantee that their priorities — on climate, health care and social welfare — will be accommodated in follow-up budget legislation. At the same time, moderate Democrats like Senator Joe Manchin of West Virginia are so far refusing to commit to supporting a massive spending bill that would be passed on a party-line vote.

Here’s how the Democrats’ two-track strategy is likely to unfold: Work Remains on Bipartisan Infrastructure Deal A bipartisan group now numbering 21 senators — 11 Republicans, nine Democrats and one independent — still has to hash out the final details of their infrastructure proposal and negotiate with the White House.