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.