There are 33 U.S. Senate seats up for grabs in 2008 -- 21 currently held by Republicans, 12 by Democrats. All but one of 13 Southern states (Florida being the exception) will choose a new senator in 2008.

Nationally, over a dozen likely won't be nail-biters, but by some estimates up to 20 could be competitive. Which Southern seats will be in play?

From the right, we have a good idea of what seats Republicans are targeting thanks to a copy of Karl Rove's PowerPoint presentation (pdf), which was presented to the General Services Administration this January, in apparent violation of the Hatch Act which prohibits partisan campaign activity on federal property. Here's how Rove's list breaks down:

ROVE: Senate seats held by Democrats, Republican targets
Arkansas
Louisiana

ROVE: Senate seats held by Republicans, vulnerable
Mississippi
Virginia

ROVE: Seats that are "not competitive"
Alabama
Georgia
Kentucky
North Carolina
South Carolina
Tennessee
Texas
West Virginia

From the left, we have a list today from Markos Moulitsas Zúniga at DailyKos of races that "are or might be interesting by Election Day 2008." He breaks them into tiers of competitiveness:

MARKOS: Tier 1 races
Louisiana

MARKOS: Tier 2 races
North Carolina
Virginia

MARKOS: "Could get interesting"
Alabama
Arkansas
Georgia
Kentucky
Texas

Let's bring in one more analyst: Charlie Cook of Cook Political Report. He's even more pessimistic about the likelihood of competitive senate races in the South. According to his latest publicly-available breakdown (from February; pdf), only three races fall outside of the "Solid Dem" or "Solid Republican" categories, and none are true toss-ups:

Lean Dem: Louisiana
Likely Dem: Arkansas
Likely Republican: North Carolina

So, to answer the question posed in the headline -- it depends on who you ask.

But to kick off the 2008 the prediction game, I'll go with Rove and speculate that at least four Southern senate races will be "in play," and that there may even be a surprising fifth that emerges by next spring. Stay tuned ...