(Image Credit: Paul Sancya/AP Photo)

In a phone conversation initiated by Mitt Romney, Newt Gingrich told Romney this morning he would suspend his campaign next week and endorse the former Massachusetts governor.

"Governor Romney reached out to say he would respect Newt's decision, but that if he was going to end his campaign, he would want Newt to be part of his team," a Gingrich advisor told ABC News.

Gingrich responded by telling Romney he had already made his decision and would work hard to help him beat Barack Obama.

When Gingrich announces the end of his campaign next week, he will also make his Romney endorsement official - an endorsement, a top Gingrich advisor says, that will be full-throated and without reservation.

"Newt believes any Republican is much stronger than four more years of Barack Obama," the Gingrich advisor said.

This advisor says Gingrich's announcement will be next week, but contrary to other reports, it will not be on Tuesday.