While Fred Thompson‘s announcement that he was considering a 2008 presidential run was enough to drop his opponents’ poll numbers, the Tennessee actor/politician may be running into a time crunch. Vanderbilt political scientist John Geer says Thompson may need to hurry up and make his decision, or risk losing his chances for a successful run. The same advice goes for Al Gore (he says he’s not running, but the pundits still speculate). At some point, the two men (and any other undeclared candidates) will be too far behind in fundraising and organization to catch up with the rest of the field. Read more of Geer’s insights at VUCast.