Sen. Barack Obama has proposed $18 billion annually in new spending on education. But, if elected, will he actually be able to increase spending substantially in tough economic times?

Tonight’s prime-time 30-minute ad may offer a clue as to whether education policy would be a high priority in an Obama administration. The Democratic presidential nominee is scheduled to address the nation on the FOX, NBC and CBS networks during prime-time to deliver his “closing arguments” speech.

Neither presidential candidate has talked much about education on the campaign trail. And some inside-the-Beltway folks I’ve talked to think that means schools may have to play second fiddle to other domestic spending priorities, particularly energy and health-care, at a time when the federal government - and the rest of the nation - is strapped for cash.

Many people in Washington think it’s unlikely Obama would really be able to increase spending by $18 billion—the money just isn’t going to be available. But, if Obama makes a point of promising a huge new investment in such a high-profile forum, even after the economic meltdown and the $700 billion financial assistance plan for Wall Street, it would be a sign that he’s serious about seeking an increase in education spending. At the very least, it would give education voters something to hold him accountable to if he wins and his very first budget, released early next year, doesn’t deliver the goods.