U.S. presidential hopefuls signal they won't go gently into Sanders's good night if he falls short of majority

Bernie Sanders has been warned that he might need to watch his back at this summer's Democratic convention.

The U.S. senator's rivals have raised the possibility of pushing him out on a second ballotif he enters the convention with a lead short of a first-ballot majority.

That was the subtext of a revealing exchange in a presidential candidates' debate Wednesday night in Las Vegas.

That brief banter might not garner headlines as it came at the tail end of an unusually caustic debate sprinkled with memorable sound bites.

What's more likelyto command public attention were other improbable quips that emanatedfrom the debate stage they include the phrases "fat broads," "horse-faced lesbians," and "Are you trying to say that I'm dumb?"

But that subtler exchange laid bare a scenario that Democratic strategists are increasingly anxious about: mayhem at the party's national convention in Milwaukee in July and a divided party facing U.S. President Donald Trump.

Debate moderator Chuck Todd asked candidates about the possibility that nobody will enter the convention with more than 50 per cent ofpledged delegates.

The scenario seems increasingly plausible, with Sanders now clearly the front-runner in polls yet still facing multiple challengers in a highly fragmented field.

And it's unclear that anyone will have time to build a majority by the end of March, when two-thirds of delegates will have already been selected. The Democratic party sped up its primary calendar this year, with California voting earlier.

Only one candidate on stage replied that the person leading on the first ballot should be guaranteed the nomination: that was Sanders.

All the rest pointed to the party rules if thefront-runner on the first ballot does not have a majority of pledged delegates, he or she can be overtaken on subsequent ballotswhen superdelegates factor into the vote.

It hasn't happened in decades in the U.S., though it's quite common and uncontroversial in Canadian leadership contests. One needs only ask Andrew Scheer and Stphane Dion, who both leapfrogged rivals and claimed the leadership after multiple ballots.

Watch| Sanders and Democratic rivals face offover convention rules:

Showdown over convention rules

5 years ago

Duration 1:19

Should Bernie Sanders automatically be crowned the Democratic presidential nominee if he enters the summer convention with the most delegates or is it fair game for other rivals to overtake him on a second ballot? Its a scenario Democrats are starting to grapple with. In a debate, Sanders and his rivals differed over what could become a heated issue.

And some Democrats argue it's perfectly legitimate in the U.S., too.When asked whether a convention front-runner should automatically become the nominee, former vice-president Joe Biden replied: "No."

Superdelegatesstart voting at 2nd ballot

What the rules say is that party officials, better known as superdelegates, get to start voting as of the second ballot.

Those so-called superdelegates would account for about 15 per cent of votes on subsequent ballots.

There were answers similar to Biden's from former South Bend, Ind., mayor Pete Buttigieg; Minnesota Sen. Amy Klobuchar; and billionaire businessman and ex-New York mayor Michael Bloomberg. (Sen. Elizabeth Warren's answer was less clear.)

Their sentiment is shared by some party organizers known to Canadians, including some former U.S. ambassadors to Canada under Democratic presidents who remain active in Democratic politics.

"The rules are the rules," said Bruce Heyman, a Barack Obama-appointedenvoy to Canada who supports Klobuchar.

"Remember,this is a convention of the party and the party needs to select the nominee that they think will best represent the party and be most competitive to win versus Donald Trump. That may mean Bernie is the nominee. It may mean someone else is the nominee in a brokered convention."

Party strategists have been dreading another divisive convention.

WATCH | Democratic candidates target Bloomberg during debate:

Bloomberg under attack

5 years ago

Duration 1:00

Rivals pounced on Michael Bloomberg, the billionaire ex-mayor of New York, in his first presidential debate. Sen. Elizabeth Warren was first to unload on his record, which has included numerous complaints from former colleagues about alleged sexually inappropriate remarks.

Angry walkouts by Sanders supporters cast a shadow over the 2016 Democratic gathering, revealing party divisions that undermined Hillary Clinton. Sanders sounds ready to push back. He cast doubt Wednesday on the democratic legitimacy of such second-ballot strategizing.

"The process includes 500 superdelegates on the second ballot. So I think that the will of the people should prevail yes," he replied during the debate.

The next few weeks should decide whether or not this scenario surfaces. By the end of March, more than 2,600 delegates (out of 3,979) will already have been assigned, making clearer whether anyone is trending toward a first-ballot majority.

Bloomberg is a new wild card in the race.

The billionaire has already pumped record-breaking sums into campaign ads, orders of magnitude higher than all the spending in a Canadian election by all parties combined.

He's been rewarded with an instant spike in the polls, but it's not yet clear what effect he'll have on the results.

Rivals repeatedly attacked Bloomberg during debate

A late entrant, Bloomberg begins appearing on ballots as of Super Tuesday, March 3 only then will it be obvious whether he's harming Sanders (by consolidating the anti-Sanders vote), or inadvertently helping him (by further splitting it). He was knocked off-stride at the outset of his first televised debate.

Warren came at him early, alluding to scores of allegations, including a number from women in court filings, about inappropriate sexual comments in the workplace.

Referring to some of those allegations, Warren said: "[There's] a billionaire who calls women 'fat broads' and 'horse-faced lesbians' and, no, I'm not talking about Donald Trump. I'm talking about Mayor Bloomberg. Understand this: Democrats take a huge risk if we just substitute one arrogant billionaire for another."

Biden pushed the ex-mayor to lift non-disclosure agreements on former employees and let them speak publicly.

Bloomberg brushed off that request, speaking tentatively.

WATCH | Bloomberg and Sanders get into heated exchange about socialism:

Clash over communism

5 years ago

Duration 0:58

In his first presidential debate, billionaire ex-New York mayor Michael Bloomberg appeared to liken Sen. Bernie Sanders socialist inclinations to communism and said it would lead to an election loss and the re-election of Donald Trump. Sanders called that a cheap shot, in a heated exchange about socialism.

He spoke more aggressively later in the debate, when Sanders called his wealth and influence on politics an outrage.

Bloomberg likened the Vermont senator's policies to communism, and said they would prove politically fatal in a general election.

After one exchange with Sanders, Bloomberg said: "I can't think of a way that would make it easier for Donald Trump to get re-elected than listening to this conversation."

Another wince-inducing exchange came when Buttigieg mocked Klobuchar for forgetting the name of Mexico's president, calling into question her mastery of files in Washington.

"Are you trying to say that I'm dumb? Are you mocking me here, Pete? I made an error," Klobuchar said. "People sometimes forget names."