If President Barack Obama does win a second White House term on Nov. 6, it will almost surely be because he was running against Republican nominee Mitt Romney. If, on the other hand, GOP challenger Romney were to prevail, the almost certain reason will be because he ran against incumbent Barack Obama. Both Obama and Romney desperately need each other to make this election not a referendum, but a choice.

Consider the president's problems as recorded in the most recent NBC News-Wall Street Journal poll.

Asked if they thought "things in the country are generally headed in the right direction" or "are off on the wrong track," by a 2-to-1 margin (61 percent to 32 percent), voters now judge the U.S. to be "off on the wrong track."

True, George W. Bush was narrowly re-elected in 2004 when voters — by just a 5 percent margin — saw the nation "on the wrong track." But Presidents Bill Clinton in 1996 and Ronald Reagan in 1984 won decisive re-election victories when voters believed the nation was headed "in the right direction."

In 1992, when 69 percent of Americans felt we were "off on the wrong track," President George H.W. Bush lost while watching his vote total fall by 16 percent from four years earlier.

"Compared to when Barack Obama became president — do you think that the country is better off, worse off or about the same?" Fewer than one-third of voters (31 percent) think the country is better off under President Obama, while 42 percent see the U.S. as worse off after four years.

When asked, "How confident are you that Barack Obama has the right set of goals and policies to improve the economy — extremely confident, quite confident, only somewhat confident or not at all confident," two out of three voters answered either "not at all confident" (44 percent) or "only somewhat confident" (22 percent). Hardly a ringing vote of confidence.

These are not the kind of numbers that ordinarily would win anyone a second presidential term.

Unless, that is, the incumbent were lucky enough to be running against an opponent — Mitt Romney — who, when voters were asked to rate their "feelings toward" as "very positive, somewhat positive, neutral, somewhat negative or very negative," was rated positive by just 38 percent and negative by 44 percent.

What about the question of "how confident are you that Mitt Romney has the right set of goals and policies to improve the economy — extremely confident, quite confident, only somewhat confident or not at all confident?" Nearly three out of four voters went thumbs-down on the former Massachusetts governor's economic proposals, rating them either "not at all confident" (42 percent) or "only somewhat confident" (31 percent).

The poll asked, "Who do you think would be better" — Democrat Obama or Republican Romney — "when it comes to caring about average people?" The verdict: Obama 52 percent and Romney only 30 percent.

It is difficult to see how, given voters' negative feelings toward Romney personally as well as their lack of confidence in his economic platform, the challenger could ever get to 51 percent. But, given the same voter disappointment or disaffection with the Obama record and the general malaise about the perceived wrong direction the country is headed, it becomes obvious that the president has to hope that voters will heed the earlier advice of Atlanta Mayor Kasim Reed to compare Obama "not to the Almighty, but to the alternative."

What we have on the eve of the two party conventions and the final lap of this presidential triathlon is two candidates who seemingly are unable to win on their own but who desperately need each other to be compared to.

To find out more about Mark Shields and read his past columns, visit the Creators Syndicate web page at www.creators.com.