The yearly battle over the U.S. budget officially begins on Feb. 2, when the president plans to send his fiscal 2016 funding proposal to Congress, where it will be torn to shreds or ignored entirely.

While the annual drama involves trillions of dollars, it's usually of limited interest to far-flung governments around the world. Not this year, though, thanks to a budget line item whose fate will be closely tracked by an international audience.

The line item of interest is President Barack Obama's expected request for money for the Green Climate Fund, which is a key component in the push for a global agreement this year to limit global warming. The fund is meant to collect and distribute money from developed nations to help poorer and developing countries lower future carbon emissions and prevent further damage from the effects of climate change.

It's unclear how much GCF money will be included in the upcoming budget, but Obama pledged to provide $3 billion over the next four years. Whatever the amount, it will be under attack from Congressional Republicans who question the science behind climate change and have vowed to block any related funding, including Obama's pledge to the GCF.

The pledge from the U.S. is a particularly important one. The $3 billion offer represents about 30 percent of the GCF's total pledges to date of $10.2 billion. Since the U.S. is the world's largest historical polluter and the second-largest economy, many negotiators had hoped for a larger financial commitment.

A final budget typically gets hammered out late in the year, which is about when world leaders will begin gathering in Paris with hopes of signing a historic climate treaty. If money for the GCF isn't in the budget, it could undermine assurances made to developing nations that the world's biggest polluters stand ready to help them.

"A signal that President Obama is not able to get GCF funding approved by the U.S. Congress would send a very damaging signal [for Paris]," said Liane Schalatek, who has attended GCF board meetings on behalf of the Heinrich Böll Foundation North America, where she is associate director.

The success of negotiations in Paris "very much depend on the fulfillment of promises that people made," said Karen Orenstein, a senior analyst at Friends of the Earth who focuses on climate finance. "Everyone, but particularly developing countries and civil society, will be looking to see if the money is realized."

In mid-December, GCF supporters got a glimpse of the funding fight ahead, and it wasn't encouraging.

That's when Congress passed a $1 trillion omnibus spending bill that covers government funding through September 2015. It included language that at first seemed to prohibit Congress from providing money to the GCF, and it shocked the fund's backers.

"The panic stemmed from the headlines that said things like, 'Congress Bans Money for Green Climate Fund,' but they were false," said Orenstein. She offered her own interpretation of the bill's language: "It basically says no money is going to be appropriated to the GCF in FY15, because no money has been requested, and if they do want money in FY16, they have to notify the committee on appropriations."

The angst was not entirely misplaced, however. The bill that passed included several provisions that angered environmentalists, including one that prohibited the Environmental Protection Agency from applying Clean Water Act rules to farm ponds and irrigation ditches. And being singled out in the 2015 bill, as the Green Climate Fund was, confirms that it's on some Republicans' hit list.

Schalatek called the budget move "a clear 'call-to-arms' by the Republican congressional majority to focus on undermining President Obama's international climate agenda."

GCF supporters remain hopeful, though, especially since under the Bush Administration, Republicans supported much higher funding for climate-related international aid.

"I have no doubt that it will be a huge fight to get this money, but I don't think it's impossible," Orenstein said. Friends of the Earth and many other groups will be pushing for the funding. Even so, she added, "I hope the treasury and state departments have a good plan for how they're going to tackle this."