Defense Amendment Watch: Some reports indicate that Webb's troop rotation amendment could be inching closer to the crucial 60-vote mark. It currently has, it's estimated, 57 votes, so 3 more are needed. The measure is backed by most Democrats and a few Republicans, and it sounds like 4 more Republicans are considering switching to back Webb:

“I’d like to find reasonable ways to limit some in a volunteer army on how long our military men and women are expected to serve, but I don’t want to vote for something that will become a backdoor deadline,” said Sen. Lamar Alexander (R-Tenn.), who added he was “studying” the Webb amendment to determine whether it could win his support this time around.
The other three Republicans — Sens. George Voinovich of Ohio, Lisa Murkowski of Alaska and Elizabeth Dole of North Carolina — all said Tuesday they were considering whether to reverse course and support the measure.

If three of these four switch, Webb's amendment would pass (if nothing else changes)...
UPDATE: But it looks like something may have changed. This Politico story suggests that some of the backers of this amendment no longer believe that Warner (R-VA), who previously voted in favor of this amendment, will back it. If so, that sets Webb and supporters back to 56--and in need of 4 more votes.