“I like Elizabeth Warren. [optional]” the script begins. “In fact, she’s my second choice. But here’s my concern about her.” It then pivots to the criticisms of Warren.

The Sanders campaign did not challenge the authenticity of the script, but declined to comment. The Warren campaign also declined to comment.

It is not clear whether the script is being used for phone calls or door knocking or both, or in which locations.

The document also instructs to tell voters who are favorable toward Pete Buttigieg that he lacks support among African Americans and young people, and to tell voters sympathetic to former Vice President Joe Biden that “he doesn’t really have any volunteers” and that “no one is really excited about him.” All of the attacks relate to the electability of Sanders' top rivals.

The campaign script signals a break from the predominantly positive tone that the Warren and Sanders have adopted throughout the campaign. While Sanders has been critical of other Democratic rivals, particularly Biden, he and Warren, longtime personal friends , have largely abstained from attacking one another despite regular prodding from reporters.

But with voting now just weeks away, the competition between the two is intensifying. The marquee Iowa Poll released Friday had Sanders in first at 20 percent, with Warren trailing narrowly behind in second place at 17 percent.

“We were told never to go negative or contrast with other candidates,” a person close to Sanders’ campaign told POLITICO. “Bernie would let us know when it was O.K.. So if that’s happening, he’s aware.”

The quasi-truce between the two has had moments of friction but has largely held. Last summer, some Sanders aides took to Twitter to criticize Warren’s positions on Medicare for All, for not going on Fox News, and more.

The Warren campaign did not respond publicly. But Warren’s senior adviser Dan Geldon privately communicated with Sanders’ campaign manager Faiz Shakir in an attempt to stop the tweets, according to an official familiar with the conversation.

The number of critical tweets did decline, but some Sanders aides, including policy adviser Warren Gunnels, have continued to occasionally jab at her.

The Sanders script is a sign that the Sanders campaign is starting to go after all the candidates more aggressively, not just Warren. When volunteers encounter voters leaning in favor of Biden, they’re told to respond that there is no enthusiasm for the former vice president and that Trump would “clobber him on his Iraq war vote, for instance, and his support for free trade agreements. That's exactly what Trump did with Hillary and it's part of why Hillary lost,” according to the script.

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“Joe Biden would crush Donald Trump in a general election,” responded Biden spokesperson Andrew Bates. “There’s no constituency in our party waiting to simply reward whomever attacks other Democrats the most — especially not during the most high stakes election of our lifetimes.”

Buttigieg spokesperson Chris Meagher said that the former mayor “is offering leadership that will turn the page on the exhausting division and dysfunction coming out of Washington.”

Sanders has increasingly been stressing that he is the candidate best positioned to defeat President Donald Trump. At three stops during a swing through Iowa this weekend — his first trip there since the Des Moines Register poll was released — Sanders stressed his electability and previewed how he would run against Trump. He also seized on Trump and his campaign’s comments about Sanders in recent days, which came after months of the president’s team largely ignoring Sanders.

“The truth is that Trump understands that we can beat him because in the last few days, if you have heard what he is saying, what the Republican Party is saying, they understand that we are their threat,” Sanders said at a coffee shop in North Liberty. “For once, they got it right! I gotta admit.”

The Sanders script also makes an electability argument with voters who may be concerned about his left-wing views.

“Status quo candidates lose,” the script reads. “Every candidate — both Democratic and Republican — who has run as the safe bet for the past two decades has lost.” It goes on to note that Al Gore, John Kerry, Mitt Romney, and John McCain all failed to win the White House. “Every single one.”

