Tuesday night may have been the last time Barack Obama and Hillary Clinton would face off in a debate this primary season. Not only because Hillary’s candidacy is hanging by the fraying thread in Ohio and Texas, but remarkably because she can no longer be confident of winning these contests.

It used to be a given that Hillary, policy wonk and master of detail, would outshine Obama, master of the set speech and crowd pleasing rallies. But in the same way he beat her in fundraising and organization, he eventually proved to be her equal around the debate table. At every turn she sought to expose his weakness, only to have the effort backfire.

At the root of this problem is Hillary’s need for an opponent to demonize in order to define herself. In Arkansas it was teachers’ unions who opposed merit pay and other education reforms. In the White House it was the insurance industry who opposed her efforts to reform health care. She succeeded in getting legislation passed in Arkansas while failing miserably at health care reform, but the pattern can be seen throughout her career. Pick an enemy and attack.

Hillary was always most comfortable battling the infamous Vast Right Wing Conspiracy. When she was fighting Republicans and defending her husband she had the natural support of her party; and many in the country who thought the GOP was over-reaching. She even managed to leverage this into a Senate seat.

In her presidential campaign, this ability to survive was to be her trump card. She proclaimed herself the only one tough enough to win in November. There was only one small problem: she had to win the primary first.

In this scenario who was to play the foil for her attack politics? At first it was George W. Bush. But this only goes so far as she wasn’t running against Bush and he wouldn’t be on the ballot.

At some point she was going to have to articulate a vision of the future. But her entire rationale for running was tied to the past; her money, her name recognition, her popularity were all tied to nostalgia for the economic good times of her husband’s administration. How could she run on “change” when she was the epitome of an establishment candidate?

When push came to shove Hillary’s instincts kicked in and she sought to run against someone rather than on where she would take the country. Her constant touting of her “experience” was in clear contrast to Obama’s inexperience. Her solutions were in contrast to his mere rhetoric.

But once Obama proved to be more than a lightweight good at speeches Hillary was at a loss. Obama had set a trap. He was explicitly running on a new approach to politics and against the old attack style politics with which Hillary was most comfortable. He was seeking to move beyond the very battles she was running on.

She seemed to believe she could knock him out on details and “gotcha” moments. But she attacked in a way that pushed her to the left and weakened her own credibility. Despite his being the most pro-abortion candidate in history she tried to portray him as weak on abortion. This resulted in a shrug from most voters and a backlash from national feminists.

When surrogates raised the issue of Obama’s admitted drug use she looked desperate or unable to control her campaign or both. The same was true when Bill failed to control his temper and harshly attacked Obama.

Recently, Hillary lamely attempted to use accusations of plagiarism to deflate Obama’s rhetoric and got caught up in a distracting debate about his wearing traditional clothes while on a trip to Africa.

When all of these gambits failed she was left complaining about the one opponent she has always hated: the media. This has long been her fall back enemy. When all else fails blame the press. And while there is no shortage of disgust for the media on either the left or the right, this tactic has never been known to win over voters.

What attracts voters are a clear and simple message and a candidate who can credibly embody it. This is the weapon Hillary lacks. “I will work hard” just doesn’t cut it. Hillary keeps tangling herself up in what the first President Bush referred to as the “vision thing.”

Hillary gained the White House the first time thanks in large part to this Bush weakness. Now it looks like someone who excels in this area is going to prevent a return trip.

Hillary is finding out that in politics, as in life, what goes around comes around.