WASHINGTON — President Joe Biden used his early months in office to lay out a sweeping agenda for what he hoped would be a transformative presidency.

But when one of Democrats’ highest priorities — a massive voting rights bill — crashed to defeat in the Senate this week, it delivered a sobering reminder of the constraints Biden faces, and the limits on what he may be able to accomplish.

Even as Biden made progress Thursday on his plans for a major infrastructure package, many of his other major policy goals face the same Senate roadblocks: a 50-50 party split, entrenched GOP opposition, divides within his own party, and the filibuster. That Senate supermajority rule means even when Democrats stick together, they still need 10 Republican votes for most of what Biden wants to do.

It’s a reality increasingly frustrating some Democrats who, with complete control of Washington for the first time in a decade, harbored hopes of action on police reform, racial inequality, guns, immigration, climate change, and the minimum wage. Instead, the failure of the voting bill and the obstacles to changing or eliminating the filibuster have progressives worried that a bold agenda will wither, a rare opening will be wasted — and harsh political consequences will follow.

“People expect the Democratic Party to deliver,” said Rep. Ro Khanna (D., Calif.), a progressive originally from Bucks County. “There’s a huge expectation on all of us. We have the House. We have the Senate. We have the presidency. What more can you ask for?”

Voters, he said, don’t want to hear about Senate procedure: “Eventually people will roll their eyes.”

If so, Democrats could face peril in next year’s midterm elections and the 2024 presidential race.

Biden “can’t go back to voters in 2024 and ask voters to reelect him based on no accomplishments other than the American Rescue Plan,” said Tré Easton, of the progressive group Battle Born Collective, referring to the sweeping stimulus package enacted in March.

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Polling backs up his point. While Biden’s proposals are broadly popular, his personal approval rating stood at 48% in a Monmouth University survey released last week, down from 54% in April.

“I think it happened now specifically because it looks like a lot of the early promise is getting bogged down,” said Monmouth pollster Patrick Murray.

Biden did take steps toward another potentially significant achievement Thursday when he and a bipartisan group of senators agreed to the outlines of an infrastructure package that would invest nearly $1 trillion, including more than $500 billion in new funding, in roads, bridges, broadband, and other projects. In the kind of image he promised during the 2020 campaign, Biden stood in front of the White House flanked by senators from each party and announced: “We have a deal.”

But there are huge hurdles to passage. Some progressive Democrats immediately complained the package was too narrow, and less than 24 hours after the deal was sealed some of Biden’s GOP partners were balking over the president’s statement that he’ll only sign the final bill if a second, bigger and likely Democrat-only package also cleared Congress.

Even if the bipartisan plan becomes law, it illustrates the limits Biden faces. It would cover only a fraction of the $4 trillion infrastructure, jobs, and families package he first proposed, and could exclude many of his policy initiatives — such as plans for child and elder care, and tax hikes on corporations — though he hopes more will come through the second piece of legislation.

“I’ve been president about 150 days, I think I’ve done fairly well so far,” Biden said at the White House. The infrastructure deal, he said, will create jobs and ease the burdens on working families, “but it also signals to ourselves and to the world that American democracy can deliver.”

While the deal represented another gain on economic policy, his promises on social issues face steep climbs.

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Worried progressives mainly blame Republicans, who they argue have done nothing but obstruct the last two Democratic presidents (though Republicans’ first filibuster under Biden didn’t come until late May, to block a commission to investigate the Jan. 6 Capitol riot).

But they say Republican opposition was to be expected, and are increasingly urging their party to show more force — primarily by ending or modifying the filibuster.

“We have to kill it and I think the president needs to be more aggressive with pushing for this very good agenda that he just needs to follow through on, and the Democratic Party has to get in line,” said Nicolas O’Rourke, the Pennsylvania organizing director of the progressive Working Families Party.

The issue, he said, isn’t a Senate technicality, but real-world impacts of proposals stifled by inaction. He pointed to the voting rights measure, pitched as a counter to Republican-led state legislatures, including Pennsylvania’s, that are passing or considering bills that would often make voting more difficult.

“This is really about Black folks’ agency in the USA ... making sure that we have access to the ballot and that it’s not an obstacle to poor and working-class people,” O’Rourke said.

Others cited the importance of raising the minimum wage and fighting climate change as urgent, tangible priorities. The top Pennsylvania Democrats running for U.S. Senate have made abolishing the filibuster a central promise.

But the rule appears likely to stay for now, since a number of Democratic senators, including Joe Manchin of West Virginia and Kyrsten Sinema of Arizona, still support it.

Both of Biden’s immediate predecessors, Trump and Barack Obama, ran into similar constraints — even with more political leeway than Biden, who took office with one of the slimmest congressional majorities in modern history.

Republicans say the problem is that Biden has embraced a radical agenda.

“The Democrats of course would like to really remake American society in so many ways,” Sen. Pat Toomey (R., Pa.) said in a television interview this week. “To do so they’d have to get rid of the filibuster so that they could jam their agenda through on a party-line vote.”

Toomey was speaking specifically about the voting bill, but his comment echoed GOP resistance to Biden’s wider agenda.

Biden can point to some significant early accomplishments, and the possibility for more soon.

The $1.9 trillion relief plan included a raft of Democratic priorities, including a Child Tax Credit expansion that could aid nearly every family with children, and cut child poverty in half. Vaccine distribution has fallen short of his July 4 goal but has gone far enough that for many people normalcy has returned in time for summer. The economy is growing.

Along with the infrastructure compromise, Senate talks are ongoing over gun laws, and congressional negotiators on Thursday announced a ”framework” for a deal on police reform. Biden also plans to use a second round of reconciliation, the Senate procedure that skirts the filibuster, to pass an even bigger infrastructure plan in tandem with the compromise package, fulfilling more of his vision.

But narrow Democratic majorities, and GOP concern, mean both pieces still face significant uncertainty.

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And issues such as voting rights and immigration likely can’t be handled through reconciliation, which is limited to tax and spending policy. A $15 minimum wage was axed from the stimulus package because it didn’t comply with those rules. The Child Tax Credit was limited to one year for a similar reason. It will take more legislation to make that a permanent legacy.

Liberals hope the voting bill’s defeat will catalyze more aggressive action. They have promised an intense campaign to pressure Democrats who still support the filibuster.

Sen. Bob Casey (D., Pa.) said Democrats have to “use every tool at our disposal.”

“We won the election,” he said, “we’re going to govern, we’re going to deliver for American families.”