The bad blood between “Good Morning America” co-host Diane Sawyer and her former partner Charlie Gibson is about to boil over — after ABC offered Gibson’s “World News Tonight” anchor seat to Diane, sources say.

Gibson, 63, won’t leave the “World News” anchor desk until after the presidential election in 2008, but insiders say ABC execs were desperate to keep Diane at “GMA” when her contract expires next spring.

Diane and Charlie’s “friendship crashed and burned this summer when he beat Diane to the punch and escaped the dreaded ‘dawn patrol’ they both call ‘Good Morning America,'” said a studio insider.

In our Oct. 30 issue, we reported that 61-year-old Diane desperately wanted to anchor ABC’s evening news.

When Gibson got the gig, she secretly planned to walk away from “GMA.”

While an ABC publicist denied Diane was considering leaving “GMA,” we reported rival network NBC was angling to sign the brainy blonde.

“Charlie’s escape to host the nightly news made Diane so angry, word got out that she was planning to bail from ‘GMA’ in 2007, when her contract expires,” said an inside source.

“That panicked the network execs into doing whatever it took to keep Diane. The last thing they wanted was her signing on with an enemy network — like NBC.”

The studio insider added: “Knowing Charlie, he’ll be the same gracious gentleman he always is when the big changeover happens.”