Six men with the rank of general during the Civil War went on to become  president of the United States. But a new kind of union battle — one being fought in places like Trenton and Madison and Columbus and Indianapolis — may be forging the next generation of leaders who will ascend to the White House. How state governors fare as commanders in this escalating conflict with Big Government Labor may determine who makes it all the way and who falls short.

For the most part, the political backlash against public unions is happening in the states. That’s where employee benefits are creating long-term budget problems. Total unfunded pension and healthcare liabilities could be as much as $3.5 trillion.

Savvy governors can thrust an issue like public sector compensation into the national consciousness and create a political niche for themselves.  And American voters like to promote state bosses  to national CEO. President Barack Obama was never a governor, but two-term predecessors George W. Bush, Bill Clinton and Ronald Reagan all were. The last sitting U.S. senator before Obama to go directly to the White House was John Kennedy in 1961.

In New Jersey, Chris Christie’s efforts at austerity have made him a leading 2016 GOP contender with many Republican activists still hoping he’ll change his mind and make a run against Obama next year. Wisconsin Republican Scott Walker has burst into national prominence by trying to strip public unions of some bargaining rights. And in liberal New York, Democrat Andrew Cuomo’s adversarial approach to labor might help his centrist appeal should he cast an eye on the Oval Office.

Among Republican activists, it’s almost impossible to be too tough on unions. That’s where the risk of overreach starts cropping up. Indiana’s Mitch Daniels, a possible 2012 candidate, already has killed collective bargaining for state workers. Yet conservatives balk because he won’t prohibit making union membership a condition for employment. Daniels sees that as a needless fight with organized labor, whose influence is already waning. As Josh Barro of the Manhattan Institute notes on his blog:

As of 2010, only 8.2 percent of private-sector workers in Indiana were members of unions. That’s a bit above the national average of 6.9 percent, owing to the state’s industrial base, but it’s also falling faster than in most states: down 37 percent in the last decade, compared to 22 percent nationally. Private firms don’t appear to fear excessive union power in Indiana; indeed, the state has had significant success in drawing non-union Japanese auto factories.

The political subtleties sometimes get lost in the heat of battle. Some in the Tea Party are bashing Christie for increasing the state’s spending in his newly announced budget. But the governor is trying to negotiate a deal with Democrats to go easier in exchange for sweeping pension reform. And if Walker should settle for something less than total surrender or go too far by firing workers, his sudden ascent could come to a halt.

The fight against public unions and for fiscal responsibility may look like to create a clear path to the presidency for now. But governors going down that road will need to beware of the many political mines strewn along the way. Still, a future American president may have his or her mettle tested in this new civil war.