The survey, conducted by the Philadelphia Inquirer, still gives Casey 49-percent support to Smith's 42-percent support, a 7-percentage-point lead. However, the last Philadelphia Inquirer survey of the race, conducted the first week in October, gave him a 10-point lead on the challenger.
And Casey has seen his popularity diminish significantly since that early-October poll. Voters are now about evenly split in their opinion of him, with 38 percent viewing him favorably and 37 percent viewing him unfavorably. Smith is viewed favorably by 34 percent of voters and unfavorably by 23 percent.
The new poll comes as other surveys of the race seem to show a tightening, and an outside democratic group, Majority PAC, launched an ad buy in the state, but national GOP groups have not yet entered the race -- in part because Smith has considerable personal funds to boost his own campaign.
That's the reason Majority PAC gave for entering the race, saying in a statement that the group's buy was needed because "self-funding candidate Tom Smith has bombarded the airwaves in recent weeks."
But as the same Philadelphia Inquirer poll shows Obama's lead diminishing slightly, Democrats may have reason to worry that their fortunes are waning in a state that formerly looked like a sure thing for the party. With 12 days to go, if this trend continues, Pennsylvania may see a late influx of cash from both sides in an attempt to sway the state in their favor.
The Philadelphia Inquirer survey was conducted among 600 likely voters from Oct. 23 through Oct. 25 and has a margin of error of plus or minus 4 percentage points.