John McCain likes to hold himself out as a fiscal conservative, and compared to Barack Obama there is no comparison. McCain expresses concern over the mountains of debt that George Bush and his willing accomplices in Congress have left for future generations, and has put forward modest plans for reversing these ominous trends. For example, the Republican pledges to freeze some government spending — with the notable exclusion of the military budget, veterans benefits, and entitlements — and perhaps to eliminate certain federal agencies, although in last night’s debate he didn’t stipulate which ones. Obama will not commit to similar steps to halt the runaway train of federal spending, and his tax increases are unlikely to generate nearly enough revenue to offset his proposed spending increases, and may well make the fiscal imbalance worse by stifling entrepreneurship and job creation.

But McCain’s specific proposals don’t add up to considerable savings. For example, last night he cited his opposition to the Boeing tanker deal, which he claimed saved taxpayers $6.8 billion (back in June, McCain put the figure at $6.2 billion). He has mentioned his opposition to earmarks, which total $18 billion. In the previous debate, he suggested that eliminating cost-plus contracts would save money in the Pentagon, but he didn’t venture a guess as to how much. Such modest proposals invited Obama counterattacks: the Democrat noted that the costs from the Iraq War, which McCain has pledged to continue until we achieve “victory,” would erase McCain’s vaunted earmark savings in less than two months.

Beyond sparring over Iraq War costs, however, the two candidates have not been pressed to justify their plans for military spending.

Personnel costs constitute roughly one third of the total defense budget, and are likely to grow in 2009 regardless of who wins next month’s election. Both McCain and Obama support President Bush’s decision to increase the size of our ground forces by 92,000 men and women over a five-year period. It is curious that Obama, a man who wears his opposition to the war in Iraq like a badge of honor, would support such increases. If Obama gets his wish, and removes most U.S. military personnel from Iraq over a 16-month period, he will presumably have more than enough troops to surge some into Afghanistan, while still reducing the burdens on our men and women in uniform, and their families. So, why the need for still more troops? Where else would a President Obama send them? Darfur? Congo? Burma? Georgia? He hasn’t said.

But leaving that aside, the scheduled increases are not nearly enough for John McCain. Writing in Foreign Affairs late last year, McCain pledged, “As president, I will increase the size of the U.S. Army and the Marine Corps from the currently planned level of roughly 750,000 troops to 900,000 troops.” If McCain gets his wish, these two branches will be nearly 40 percent larger than they were prior to 9/11.

And how much will these additional troops cost? By my estimates, nearly 10 times what McCain would save if he eliminated every single earmark.

In April 2007, the Congressional Budget Office estimated that Bush’s plan to grow the force would cost an additional $108 billion through 2013. Backing out those figures — $108 billion / 92,000 — equates to $1,173,913 per additional man or woman in uniform. Applying that same number to McCain’s additional 150,000 troops comes to $176 billion.

Don’t take my admittedly crude, back-of-the-envelope estimate as gospel. According to earlier Army estimates, every additional 10,000 soldiers cost about $1.2 billion a year, so the costs of McCain’s proposal to grow the force by another 20 percent might ultimately total less than $176 billion. But if CBO pegged the earlier Bush increases at $108 billion over six years, then it seems logical to conclude that McCain’s additional 150,000 will cost still more than that.

And McCain is proposing to increase that portion of the military budget that has already witnessed considerable cost growth in recent years. The military has boosted bonuses to entice new recruits to join, and to keep those already in the service from leaving. Health care costs have also risen for the military, just as they have in the private sector. If anything, the CBO’s projections likely understate the true costs of the additional troops, because they consider only the incremental expenses associated with adding 92,000 new personnel to the system, but do not fully account for the long-term costs of keeping these troops paid, fed and equipped over the course of their military careers. Then there are the additional expenses associated with caring for more military retirees.

In two successive debates, moderators Jim Lehrer and Tom Brokaw have tried to pin the candidates down on what they would do to control spending, and both times the candidates have evaded the question. CBS’s Bob Schieffer gets his shot next week in the third and final debate. Rather than an open ended “What would you cut?” question, he might ask them how much their different plans for increasing the size of the military will cost the taxpayers.