Ohio has long been the sine qua non of Republican electoral math.  No Republican in the modern era has won the presidency without carrying the Buckeye State.

That's why the poll numbers that have emerged out of the state in recent days are so eye-opening.  The latest came from NBC/Wall Street Journal/Marist and showed President Obama at 50 percent to 43 for former Massachusetts governor Mitt Romney.  Viewed more broadly, the Real Clear Politics polling average in Ohio pegs Obama at 48.5 percent to Romney's 44.3 percent.

Take those poll numbers and combine them with the state's improving economy -- it's gotten better faster than most other swing states -- and all signs point to the fact that this state isn't a toss up but rather leans toward President Obama.

But, we're not changing our "toss up" rating on Ohio just yet. And here's why:

1. It's clear from the bulk of national and swing state polling that Obama got something of a bump from his convention.  But, given how locked in the electorate has been -- about 47 percent for Obama and 47 percent for Romney -- for months, it's hard to imagine that bump is a long-term phenomenon.  Polling over the past year or more would suggest it is much more likely Ohio returns to a dead heat than it moves further away from Romney between now and Nov. 6.

2. Ohio has been one of the most closely divided states at the presidential level for the past three decades. Since 1980, the GOP nominee has carried it five times (1980, 1984, 1988, 2000, 2004) while Democrats have won it three (1992, 1996, 2008). If you believe that 2012 will look a lot like 2004 in terms of how the electoral map shakes out, then it's hard not to imagine that Ohio is going to wind up close. (In 2004, George W. Bush won Ohio by 118,000 out of more than 5.5 million cast.)

3. Romney's campaign simply will not walk away from Ohio.  They understand that to pull money out of Ohio would be regarded as something between capitulation and panic -- neither words they want associated with their candidate in the final 50 (or so) days between now and the election.  Ohio is the crown jewel -- electorally speaking -- of the industrial Midwest, a region hit hard over the past decade by the collapse of the manufacturing sector among other economic hardships.  Putting aside the symbolic importance of Ohio, there is also a practical reason to believe that the Romney campaign will spend every dime they have to try to win the state. With neither Michigan or Pennsylvania seemingly where the GOP would like them to be in terms of competitiveness, Ohio's 18 electoral votes become all the more critical.

To be clear, you'd rather be President Obama in Ohio today than Mitt Romney. But, the history of close races in the state and the centrality of the Buckeye State to Romney's winning calculus suggest that moving it out of the toss-up category might amount to jumping the gun.