The biggest political mistakes are made when parties are most certain they are right. The nomination of Susan Rice to be Secretary of State would bring both parties into that level of certitude…and risk. However, it is undoubtedly Obama who has the most to lose.

Obama has been aggressively intent on claiming and exploiting a mandate from the November election. Nominating UN Ambassador Susan Rice to be Hillary Clinton’s replacement would fit not only with Obama’s mandate agenda, but also reinforce the demographic point November seemed to highlight. The White House relishes forcing Republicans into a fight over a minority candidate.

Republicans are equally eager to explore an issue Romney painfully fumbled: the 9/11 attack in Benghazi, which left four Americans dead. Rice sits at the pivotal point of that story: the Administration’s recognition, and then explanation, of this terrorist act. Republicans see a Rice nomination as the chance finally to have a public debate over this.

So focused on their clear opportunities, each side is overlooking equally obvious risks.

For Republicans, November’s demographic gaps had a real impact on the election’s outcomes. Their presidential candidate lost among women, who made up 53% of the electorate, 55%-44%. And they lost among Blacks 93%-6%. Opposition to Rice’s nomination could keep those cleavages fresh.

For Obama though, the risk is far greater, and more importantly, unnecessary.

The Benghazi attack was a debacle of the first magnitude. From start to finish — if the story really is finished — there are serious questions still to be asked and the answers won’t be flattering to anyone involved. However, for whatever reason, the Administration has largely gotten a pass on Benghazi.

The attack raises the ultimate Watergate question: What did you know and when did you know it? However, a Rice nomination raises an even more fundamental one first: Why would Obama want this fight?

A Rice nomination would open an issue Obama has largely escaped, thrusts it before a media that has largely ignored it, and onto Capitol Hill, the split control of which has kept this issue out of Congress. There the nomination would stay — not for hours, which the Administration has sought to avoid thus far — but for days.

And the Administration’s defense would rest on Susan Rice, whose inability to assuage her critics’ concerns in private would be put to the test in public.

All this would be done at the start of his second term, when he is trying to claim and exercise a mandate.

While it may seem inconceivable that Obama would actually bring this disadvantageous and unnecessary fight on himself, we must remember: He has done it before, on a far bigger scale, and at just such a juncture.

Fresh in office, with the economy in recession, his concerted effort with overwhelming Congressional majorities was for… healthcare overall. It consumed over a year of his presidency, failed to attract any bipartisan support, and came within a single vote of failing to pass at all. And it still remains unpopular with a majority of Americans.

Diverting his agenda to nominate Rice could again risk immediately consuming the momentum he brought out of November. He would be risking it this time, not on a policy, but on a person few people know now or will remember later, but who could turn a largely neglected issue into something that the public might come to never forget.

And this time the cost would come out of a smaller stock of political capital.

Despite his insistence on a mandate, his 2008 popular vote share was essentially halved this November. His approval rating is still only slightly above 50% and — in contrast to the large majorities he controlled in Congress in 2009 — his majority in the Senate is less and in the House, nonexistent.

When two armies choose to give battle they do so because they perceive a strength in themselves or a weakness in their opponent that the other side does not see. The problem is: Only one can be right. The able commander must do more than examine the opponent, he must also weigh the cost of failure against the reward of victory. Such a calculation in a potential battle over Rice distinctly favors Republicans.

At the end of the day, Obama will get a new Secretary of State — virtually anyone else he wants. Why then does he seemingly want this one so much?

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(The author served in the Treasury Department and the Office of Management and Budget from 2001 to 2004 and as a congressional staff member from 1987 to 2000)