Climate advocates in the Senate are worried about missing what they see as a once-in-a-generation chance to shift the nation’s spending priorities to clean energy, warning they’re prepared to hold up any infrastructure package that doesn’t deliver on that front.

Several Senate Democrats say they are willing to do whatever it takes to make sure significant climate change legislation gets across the finish line.

Green energy proponents such as Sen. Sheldon Whitehouse (D-R.I.) applauded what they called a bold vision for climate-related investment laid out in President Biden’s American Jobs Plan but have since grown nervous about a lack of progress in recent weeks as the White House and Senate Republicans have gone back and forth over a potential scaled-down bipartisan deal.

“I think there is a significant group of senators in the Democratic caucus who are going to insist that our climate measures be robust and real and point toward 1.5 degrees Celsius, and we will do what’s necessary to accomplish that goal,” Whitehouse said, referring to a United Nations report that warming of more than 1.5 degrees Celsius compared to pre-industrial levels would lead to significantly more drought, flooding, extreme heat waves and drastic temperature drops at higher latitudes. 

Whitehouse says Senate Democrats are not yet close to that goal on infrastructure.

“We don’t even have a clear enough bill to measure against that goal,” he said.

Adding to their concerns, Senate Majority Leader Charles Schumer (D-N.Y.) hasn’t spelled out much of a plan for passing an infrastructure package other than to say the Senate will take up the matter in July.

As Washington has become focused on the stop-and-start negotiations between the White House and Senate Republicans, led by Sen. Shelley Moore Capito (W.Va.), some Democratic senators are sounding the alarm that the promise to pass a big and bold climate bill will fizzle.

Asked how far along Democrats are toward putting together an infrastructure package with meaningful climate-related provisions in case bipartisan talks between Biden and Senate Republicans fail to produce a deal, Whitehouse asked, “What package?”

“I think there are a lot of available pieces. The question is, can we reach an agreement?” he said. “And when you add up their effects, does it actually do the job?”

Whitehouse noted that the latest GOP counteroffer — a $928 billion infrastructure proposal floated by Capito and other Senate Republicans — doesn’t include any significant climate proposals.

“Dangle the bait; lure us to forgo the alternative; then slow walk us; then never get to 60. Oh, and no climate btw,” Whitehouse tweeted last week in response to a memo Senate Republicans sent to Biden laying out their position.

Proponents of the GOP infrastructure roadmap note that it includes $4 billion for electric vehicle infrastructure as well as $98 billion for public transit and $46 billion for passenger and freight rail.

Transportation Secretary Pete Buttigieg said Sunday the negotiations with Senate Republicans “need a clear direction” by June 7, a statement reflecting growing impatience among Democratic lawmakers over the pace of talks.

The Biden administration initially set a deadline of Memorial Day for significant progress in the talks but recently extended it.

Other leading Senate voices on climate change are expressing concern over lack of enthusiasm expressed by colleagues at the prospect of taking full advantage of an infrastructure bill to significantly shift the nation’s spending priorities away from fossil fuels to renewable energy.

“We’re still in the wrangling phase,” said Sen. Brian Schatz (D-Hawaii) of the discussion among fellow Democrats over how to shape an infrastructure bill when the talks between the White House and Senate Republicans collapse, as many Democratic senators expect they will.

He said it will take weeks to put together a package, while noting there are "modules that are already done and written because we’ve been ready for this moment for years, actually.”

But Schatz would like more of a recognition from colleagues that now is a rare chance to significantly address climate change and missing that chance could lead to what he and many climate advocates argue could be irreversible environmental effects.

“I’d like to see some more affirmative enthusiasm and determination,” he said. “I think this is our one moment in history to go big and bold. This isn’t about extending this or that tax credit. This is about solving the climate crisis, which means we’re going to have to not pick among the climate solutions but enact them all.” 

The Senate Finance Committee took a big step last week when it advanced the Clean Energy for America Act, a package of tax credits to incentivize clean electricity, clean transportation and energy efficiency.

The bill also ends and modifies favorable tax provisions for the coal, gas and oil industry.

The vote to move it out of committee deadlocked 14-14 on a party-line vote.

Schatz, like Whitehouse and others, isn’t enthusiastic about passing a scaled-down infrastructure bill with some Republican support that leaves climate provisions by the wayside and could make it tougher to pass a bigger package later this year by getting the most popular priorities done first. 

“I’d like for there to be only one package. But if there are two, I’d like my priorities to be first,” he said.

In the 50-50 Senate, it would only take one Senate Democrat to hold up action on an infrastructure bill that passes through the reconciliation process if Republicans are unified against it.

Climate advocates outside the Senate say they’re concerned that too much time has been wasted on bipartisan talks that don’t seem close to producing a deal.

“We’re nervous too,” said a legislative affairs director at a prominent environmental group, adding outside groups feel “the urgency to move” and warned “the clock is ticking” and “there are precious few days.”

“How do we stop this kicking the can down the road with the back-and-forth negotiations with Capito?” the strategist said.

Some environmental activists say Democratic messaging has become too narrowly focused on job creation and hasn’t done enough to highlight the opportunity infrastructure spending presents to address climate change.

Two of the top priorities of climate activists are clean energy tax incentives to encourage more private investment in renewable energy sectors and a clean energy standard that requires a minimum share of electricity to be generated from green sources. 

The overall goal is to reduce emissions, as the electric power sector accounted for nearly 40 percent of total U.S. energy consumption and 32 percent of U.S. energy-related carbon emissions, according to U.S. Energy Information Administration. 

Many climate advocates applauded Biden’s $2.3 trillion American Jobs Plan when it came out in late March. 

Its goals included moving toward 100 percent clean energy and focusing a substantial share of the benefits of clean infrastructure investments to lower-income communities.

In a bid to win the support of Sen. Joe Manchin (D-W.Va.), a pivotal centrist vote and chairman of the Senate Energy and Natural Resources Committee, the proposal calls for investing in rural communities “impacted by the market-based transition to clean energy.”

Some progressive groups allied with Rep. Alexandria Ocasio-Cortez (D-N.Y.) and Sen. Ed Markey (D-Mass.) even argue that Biden’s infrastructure plan doesn’t go far enough. They say $1 trillion a year over the next decade is needed to truly address the crisis.

Instead, the White House and Senate GOP negotiators are going in the opposite direction. The latest offer from White House officials scaled Biden’s opening bid down to $1.7 trillion, leaving some activists frustrated.

“Some in the movement were pushing for a much bigger infrastructure package to begin with,” said Ellen Sciales, press secretary for the Sunrise Movement, a youth-focused climate change group. “We are pushing for what a lot of economists and scientists have said, which is to combat the climate crisis we need $10 trillion over the next decade.”

“These bipartisan talks are just getting in the way of any future progress because we’re watering down a package that is already a compromise for us,” she added. “It just seems like a failed political strategy to go to the drawing board with the GOP.”

Updated at 7:56 a.m.