The decision on retaining Mr. Gates will be the clearest indication to date of the incoming administration’s thinking about Iraq and Afghanistan.

Like the president-elect, Mr. Gates supports deploying more troops to Afghanistan. But the defense secretary strongly opposes a firm timetable for withdrawing American forces from Iraq, and his appointment could mean that Mr. Obama was effectively shelving his campaign promise to remove most troops from Iraq by mid-2010…

“Why wouldn’t we want to keep him?” Sen. Reid said. “He’s never been a registered Republican.”