If polls are accurate, Sen. Hillary Clinton’s once-sure bid for the Democratic presidential nomination is now not so sure. Her wide lead vanished without warning in Iowa and New Hampshire — and maybe elsewhere as well.

Was it due to her waffling on issues like the Iraq war and driver’s licenses for illegal aliens? Or was her campaign too smug — like that of similarly sputtering Republican front-runner Rudy Giuliani — assuming she should be coronated by the polls and media rather than having to fight for the nomination tooth and nail?

Or is it just that her upbeat, confident rival, Barack Obama — with a little help from Oprah — is surging as he bests her in back-and-forth quips?

Hillary’s campaign is so stalled that her advisers have tried dredging up Obama’s kindergarten essays and his admitted drug use. And now they’re resorting to flying in Bill Clinton to save the day. Some polls and conventional wisdom suggest he may yet restore his wife’s fortunes.

But Bill’s not exactly a fireman. He may instead throw gasoline on the fire.

First, his vote-getting abilities are suspect. He never won 50 percent of the vote in a presidential election. That fact and the embarrassment of his impeachment were why Vice President Al Gore kept him away from his 2000 campaign. True, Bill’s presence is said to resonate with African-American voters, but most may prefer Obama anyway, as polls now show in South Carolina.

Second, Bill Clinton often comes across as a narcissist. He talks the longest and loudest about himself. It is almost impossible for first-person Bill to praise Hillary without adding, “When I was president” or “I had a vision.”

Third, Bill cannot always distinguish truth from fiction. In his rescue mission for Hillary, he has already weighed in on the Iraq war — in which he falsely claimed that he was against it from the very beginning.

Most recently, in a dig at Obama’s lack of experience, Bill claims that he nixed an earlier run for the presidency in 1988 because he saw that he wasn’t yet ready for the job. But the real reason more likely was worry about the less-than-desirable and now well-known aspects of his personal life. That tendency to dwell on — and fudge — his own past earns splashy headlines but takes attention away from his wife.

Fourth, Americans may not be comfortable with a spouse of an ex-president running for commander-in-chief. Alabama’s governor George Wallace once had his wife, Lurleen, run as his replacement when he was no longer eligible. Despite Lurleen’s victory, that staged succession seemed fishy — sort of like the current husband/wife switcheroo of former and current president Mr. and Mrs. Kirchner down in Argentina.

The Clintons need to tread carefully so that Hillary does not appear a mere bridge for Bill’s drive for a third term. When he steps in to talk nonstop in their co-defense, it appears that she’s not quite in full control of her own destiny.

If Hillary is elected president, will Bill likewise butt in when the Congress or foreign leaders are mean to his wife or her rankings tank? The last thing the would-be Democratic nominee wants is more “Bill Clinton Makes the Case for His Wife” headlines like we saw all last week.

Fifth, Hillary’s campaign can’t control Bill. Ex-presidents don’t exactly have small egos, and Clinton, something of a loose cannon, is bound to shoot his mouth off whenever and at whatever he pleases. He now brags that Hillary will send him out with George H.W. Bush to undo the damage of Bush Senior’s son, the current president.

And in a recent interview with talk-show host Charlie Rose, Bill embarrassingly gushed that Hillary “is so good.” Then he went on to trash Obama — while denying he was doing just that. No wonder that Hillary’s frantic campaign handlers were said to have been offstage trying to cut short the Rose interview.

Bill also claims that Hillary has already been “vetted” — hinting that Obama, in contrast, hasn’t been fully investigated and may well have more skeletons that someone may uncover. Yet part of Hillary’s current trouble is the public’s anger over her campaign’s past unsavory use of just that rhetorical trick: digging up dirt on opponents while claiming you’re not.

If Bill keeps this sloppiness up, some might almost wonder whether he really wants his wife to win — and thereby have her overshadow his own presidency by being both the first woman president and the Clinton who did not suffer impeachment due to self-inflicted scandal.

Hillary may yet end up the Democratic nominee. But only if she alone convinces America — and Wild Bill — that she’s running for her first, not his third, term.