Editor's note: Pentagon correspondent Jim Miklaszewski broke the news last night on our broadcast and has written this follow-up for MSNBC.com.

Although nothing is final until President Bush puts his stamp on it, administration officials tell NBC News the president has all but decided on a temporary surge of additional American forces into Iraq in an effort to bring sectarian violence in Baghdad under control. 

While no one is talking specific numbers, military officials believe it would involve some 20,000 additional soldiers and Marines.

Most of the increase would be achieved by extending the deployments of those troops already in Iraq by 90 days, and accelerating the deployments for troops scheduled to deploy by sending them into Iraq sooner.

Click here to read the rest of Jim's report.