One key thing to note is that Overby only garners 3 percent from those who've already voted while 10 percent of those who haven't cast ballots yet say they plan to back him. Republicans rightly fear that Overby will eat into Jolly's share (American Crossroads even has Rand Paul making robocalls asking people not to vote Libertarian), but the spread between Overby's actual support and putative support highlights how third-party candidates typically see their performance erode when it comes time for voters to pull the lever. If some Overby partisans keep shifting toward Jolly, that means this contest is even closer than PPP's numbers make it appear.
And the apparent Democratic improvement in the share of pre-election ballots cast, according to Pinellas County officials, doesn't look quite as impressive as it did earlier on. Republicans mailed in 43 percent of absentee ballots versus 38 for Democrats, while Democrats cast 46 percent of all in-person early votes, compared to 38 for Republicans. But only around 5,200 early vote were cast in total, compared to 117,000 absentees, giving the GOP an overall 42-39 edge. That's only a touch better for Team Blue than 2012, when Republicans had a 41-37 advantage.
As we've mentioned many times, Barack Obama carried the district that year, but by a very small 50.1 to 48.6 percent margin. Election watchers know that in off years, Democratic performance typically drops compared to presidential years, so Sink can afford very little falloff from Obama's score. In 170 elections held in 2013, Democrats ran behind Obama by an average of 6 percent and did better than the president just 16 percent of the time—and that was mostly before "if you like it, you can keep it" helped curdle sentiment even more sharply against the White House. More recent legislative special elections in Virginia have shown just how brutal the dropoff has been.
Under normal circumstances, Democrats would be at a serious disadvantage in race like this one, just thanks to the timing. Add in Obamacare and the handicap becomes even more severe. But fortunately for Sink, Republicans nominated a Washington lobbyist in Jolly, and Democrats have been able to taint him with D.C.'s stench. Sink's also outraised Jolly by a huge margin, though outside groups have helped make up the shortfall. The fact that she's kept the race this close is actually quite remarkable, all things considered.
A month ago, we felt that Sink still had a small edge thanks to her strong fundraising and the fact that she carried this district (albeit narrowly) in her 2010 run for governor. But with the election upon us, it looks like this race is now balanced on a knife's edge. As a result, Daily Kos Elections is moving this contest from Tossup/Tilt Democratic to pure Tossup.
Be sure to join us for our liveblog Tuesday night after polls close at 7 PM ET to see how it all turns out.