LE BOURGET, France - With world leaders back home, it's time for the hard-core negotiators to work on the more mundane guts of a climate deal, and they are being told to quicken their pace.

Generally climate negotiations follow a certain rhythm, veteran negotiators and observers say. Wednesday is the middle of the nitty-gritty time when the building blocks of a deal start to form.

"It's like seeing an action movie," said former U.S. climate negotiator Nigel Purvis, who is now president of Climate Advisers. "There's generally a plot, bad guys come to threaten the world. Eventually humanity rallies together and overcomes. That's the kind of thing that happens here."

For the next few days negotiators will be working to get the less-controversial subjects finished and explore possible compromises on the bigger sticking-points, all before work gets kicked up to higher levels. The lower-level negotiators have a Saturday noon deadline to come up with language for a new text of a deal that narrows the options to something the big guns start with, according to French Foreign Minister Laurent Fabius, who is the president of the climate talks.

"We must speed the process up because we have much work to do," Fabius said at a Wednesday news conference. "Compromise solutions must be found as soon as possible."

A record number of world leaders gathering in one place to discuss the single issue of climate change sends a strong signal, U.N. climate chief Christiana Figueres said. Fabius called it "strong momentum," a phrase echoed later Wednesday by chief U.S. negotiator Todd Stern.

U.S. Secretary of State John Kerry was even more effusive at a news conference of NATO foreign ministers.

"I don't think I can ever remember a time when more than 150 leaders of nations, heads of state have come together in one place for the purpose of furthering an issue of concern to all of them," Kerry said, adding that climate talks "represent one of the great security challenges of the world, as well as environmental challenges, as well as energy challenges, as well as health challenges, as well as moral obligations. And these talks, I thought, got off to an encouraging start."