WASHINGTON — Speaker Nancy Pelosi delivered a triumphant message on Friday as the House moved on legislation, long sought by environmentalists, to force the Environmental Protection Agency to regulate toxic chemicals that can contaminate drinking water.
“The Trump Administration’s E.P.A. is breaking its own promises every day that it delays and puts polluters ahead of the American people,” she said before 24 Republicans joined all but one Democrat to pass the act, 247 to 159, on the chemicals, known as PFAS. “In stark contrast, the House is taking action.”
But the measure, the PFAS Action Act, already has a veto threat looming over it, and its prospects in the Senate, like those of other House bills addressing environmental regulation and climate change, are slim to none. In the meantime, critical legislation passed in the Christmas rush last month were signed into law, with environmental provisions and climate change measures watered down or omitted altogether.
“If you really want to understand what Congress’s true priorities are, you look at must-pass legislation — you look at what they give up and what they double down on,” said Representative Alexandria Ocasio-Cortez, Democrat of New York and one of her caucus’s most outspoken climate advocates. “And if you look at must-pass legislation, this Congress is engaged in climate denial.”
On the surface, House Democrats have diligently stressed their commitment to the environment. They have held more than 120 hearings, championed legislation meant to curb planet-warming emissions and created a select committee on climate change. On Thursday, Ms. Pelosi, in teasing the release of a long-awaited infrastructure package, said it would be the House’s “most current initiative on the climate.”
But their record of legislative victories is thin. Essential legislation — a crucial military policy bill, two voluminous funding packages and an overhaul of the North American Free Trade Agreement — has passed the House, but without far-reaching environmental provisions. Even a relatively minor provision, the extension of a tax credit for the purchase of electric vehicles, was dropped from a package of tax-credit extensions at the insistence of the White House before Congress approved them last year.
“We didn’t have leadership in the Democratic Party that was ultimately willing to call the president’s bluff and say, ‘You really want to shut down the government over renewable energy? Take your best shot,’” said Michael Brune, the executive director of the Sierra Club.
Democratic leaders and lawmakers involved in the negotiations said the legislation they secured was the best they could get. The administration has prioritized undoing environmental regulations, and the Senate majority leader, Mitch McConnell of Kentucky, has made a career of defending his state’s coal industry.
The Republican position on climate change remains “absurd,” said Representative Frank Pallone Jr., Democrat of New Jersey, who is the chairman of the House Energy and Commerce Committee and an architect of another piece of climate legislation introduced this week.
But allowing the government to shut down or failing to act on a trade deal stuffed with other Democratic priorities were prices too high to pay for futile showdowns, they argue. Such spectacles would have jeopardized their House majority and doomed their campaigns to reclaim the White House and Senate.
“We’re the responsible party aren’t we?” said Representative Kathy Castor, Democrat of Florida, who leads the House Select Committee on the Climate Crisis. “No, we’re not going to shut down government. But we will live to fight another day.”
That approach has exacerbated tensions between the liberal and moderate wings of the Democratic Party.
It has also elevated fears among climate activists that Democrats, for all their passionate speeches, will not reduce fossil fuel consumption if they win the White House. The Sierra Club is already threatening to support primary challengers against House Democrats they believe have failed the movement.
“We can blame Republicans all day long, but I believe we accept some responsibility in this as well,” Ms. Ocasio-Cortez said.
Ms. Castor was not so sure. On the tax legislation Congress approved last month, she said the blame rested with the White House, which demanded the removal of tax credits for electric vehicles. Ms. Castor said Democrats fought for those and other clean energy credits “till the very end.”
Democrats refused to include technical adjustments to Mr. Trump’s 2017 tax law because Republicans would not budge on renewable-energy tax credits, according to a person familiar with the negotiations.
On the North American trade deal, which is awaiting a vote in the Senate, talks included at least one heated match over Democratic language taken from the Paris climate accord, according to one person familiar with the exchange. Democrats did not win that one, but negotiators did agree to some tougher environmental provisions, including the establishment of attachés in Mexico City solely for the purpose of monitoring Mexico’s environmental laws and regulations.
Still, at least one Senate Democrat plans to vote against the trade deal because provisions such as those are not focused enough on climate change.
“The measure is, are we meeting the urgency of the moment?” asked that senator, Sheldon Whitehouse of Rhode Island. “And we’re not even close.”
Senator Bernie Sanders, independent of Vermont, also said he would vote no on the legislation over the climate issue.
Climate activists say Democrats are failing to recognize that good policy fights make good politics. Climate change consistently polls in the top two issues for Democratic voters.
“It’s baffling that Democratic leaders didn’t listen to their constituents and try to hold the line. They seem stuck in the past and out of touch with the kind of leadership people want,” said Varshini Prakash, a founder of the Sunrise Movement, a youth-led climate group.
Democrats and environmental activists are most irate over the party’s failure to pass controls on PFAS chemicals in the annual defense policy bill.
“It was their big chance to leverage their political power to get some standards that would require the E.P.A. to regulate PFAS as a hazardous substance,” said Mary Greene, the deputy director of the Environmental Integrity Project. Of Friday’s bill passage, she said, “It’s dead in the water. It’s a gesture and an empty one.”
Representative Debbie Dingell, Democrat of Michigan and a leader in the fight against such “forever chemicals,” said her party “pushed until the end.” But, she said, “the Senate had very strong feelings about what they were going to allow.”
Some lawmakers and congressional staff said anger over the watering down of the PFAS provisions in the defense policy bill ultimately led to the passage of Friday’s narrower measure. Representative Adam Smith, Democrat of Washington and chairman of the House Armed Services Committee, was unapologetic about his negotiations with President Trump, Mr. McConnell and Senator James Inhofe, Republican of Oklahoma and the chairman of the Senate Armed Services Committee — all opponents of stricter environmental regulations.
“Throughout the negotiations, I failed in one way: I was unable to turn President Trump, Leader McConnell and Chairman Inhofe into Democrats and convince them to suddenly accept all of the provisions they despise,” he said.
Ms. Ocasio-Cortez chalked up the string of climate and environment losses to her party’s “natural risk aversion.” Environmental issues — particularly ones that touch low-income communities and communities of color — are “profoundly uniting areas for the caucus, and we gave them up,” she said.
“People say this isn’t the hill we want to die on,” she added, “but we’re going to die if we don’t do something about it.”