EXCLUSIVE: Summit Entertainment is working furiously to close the talent deals required to split Stephenie Meyer’s fourth “Twilight” novel into two films. But an unlikely roadblock is holding up an announcement — and could even lead to cast changes for the series’ final installment.

The studio is close to finalizing agreements with leads Kristen Stewart, Robert Pattinson and Taylor Lautner, all of whom will get big raises to return for a fifth installment of the vampire romance saga. And director Bill Condon is already signed to film two “Breaking Dawn” movies, which would be shot back-to-back starting in the fall and released in November 2011 and summer 2012, respectively.

But Summit is having a harder time locking in some of the franchise’s secondary characters. Deals for Peter Facinelli (who plays Carlisle Cullen) and Billy Burke (Bella’s father, Charlie Swan) are done, but we’re told the actors who play the Cullen kids (especially Kellan Lutz and Ashley Greene) are trying to sink their teeth into bigger paydays that, at least at this point, the studio behind the billion-dollar franchise is unwilling to provide. “We may have a situation where one of them is thrown out on the street to make a point,” says a source close to the dealmaking.

So are we headed for a recasting on the final “Twilight”?

There is precedent for such a tactic. After the success of the first film, Summit axed Rachelle Lefevre, who played Victoria, in part because her reps played hardball on money. (Bryce Dallas Howard got the job instead.) Now, two films into the series, even the minor Twilighters (Lutz in particular) have become sought-after stars, so it makes sense they’d want to be paid more for the final film. But we’re told that the offers from Summit — which are said to be at least 10 times what the actors made on the first movie — were deemed “offensive” given the mega-money the franchise has generated.

Summit declined to comment on the situation. But the studio wants to move quickly to pull the trigger on two movies — and it isn’t afraid to recast if deals can’t be reached. Plus, it has even more reason to be concerned about costs this time around. As is typical with blockbuster franchises, the “Twilight” movies are becoming more expensive with each installment. And the leads are going to do especially well if “Breaking Dawn” is split into two parts. The trio were initially signed for three films (remember, this was back when “Twilight” was a low-budget adaptation of a niche YA novel), but in the spring of 2009 — after the first movie became an international hit — they renegotiated all their deals so Summit could lock them for a fourth movie.

The studio then realized that “Breaking Dawn,” with its 900-plus pages and narratives told from two perspectives, was dense enough to be split into two installments (as Warner Bros. announced it would do for the final “Harry Potter” book). Just one problem: The cast wasn’t signed for a fifth movie. They’re all huge stars now, with Lautner in particular running up his quote to the $7.5 million range, so another renegotiation commenced.

That meant ponying up big-time for the leads, which will make the final movie far more expensive than the others (“Eclipse,” which hits theaters June 30, is costing around $65 million, a figure sure to be dwarfed by the fourth and fifth, even if costs can be amortized by shooting them at the same time). For that reason, Summit is still holding out the option of simply doing one “Breaking Dawn,” although multiple sources say they’d be shocked if the fifth film doesn’t happen. “This thing is gonna be two movies,” one source says. “With or without the cast intact.” Meyer has already signed off on the plan to make two, a key hurdle, given the approval rights she has in her deal.

Summit also is eyeing other cost-cutting measures for the final installments. A deal is currently being negotiated to move the production to Louisiana after making the first in Portland and the second two in Vancouver and Italy. Luring “Twilight” would be a huge “get” for the state — and, given the tax credits, a money-saver for the studio.

“Twilight” has thus far been the rare tentpole franchise made on a non-tentpole budget. It’ll be interesting to see the lengths that will Summit go to keep it there. Booting an actor from the final installment of a successful series could be a risky move, though we’re betting that as long as their precious Bella, Edward and Jacob return, fans would get over any disappointment.

Thanks to spunk-ransom