She could even decide to put the whole Democratic presidential field on blast for politicizing the impeachment process, after tweeting recently that candidates fundraising off the inquiry were “undermining credibility” of House Democrats’ probes of President Donald Trump.

“She’s laid down some of the toughest attacks of all of the debates, first against [Rep. Tim] Ryan, later against Harris,” said Democratic strategist Mark Longabaugh, an adviser for Bernie Sanders’ 2016 campaign, which Gabbard supported. “If I'm on the stage with her in this upcoming debate, I’d certainly want to be prepared to rebut or to deal with Tulsi Gabbard coming at me.”

Tulsi Gabbard's approach to foreign policy puts her outside the Democratic mainstream.
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Gabbard has begun signaling that she's looking to create a breakout moment in the upcoming debate. Last time, she criticized Harris’ foreign policy credentials in the days before she laid into Harris on criminal justice onstage. This time around, Gabbard questioned whether Warren is “prepared to be commander-in-chief” on The Hill’s show “Rising.”

"I haven't seen much come from her in the way of what kind of leadership and decision making that she would bring to that most important responsibility that the president has," Gabbard said about Warren.

Gabbard’s campaign declined to comment on its debate preparations. Asked about the debates, Gabbard spokesman Cullen Tiernan wrote in an email: “We are focusing our campaign in the New Hampshire and Iowa and reaching voters in those states person to person.”

Gabbard has not been afraid to set herself apart from others in the party during the primary, whether by criticizing others for supporting “regime change wars” or holding impeachment plans at arm’s length, warning that it would be a “divisive” process. That frankness has won Gabbard a core of committed fans, though she has never broken out in public polling.

"As she proved with Kamala, she's more than willing to say the thing other people are definitely not willing to say," said Democratic strategist Julia Barnes, the national field director for Sanders' 2016 campaign.

"You just have to balance that with the fact that the other half of the sh-- she says is so completely off message for the party and the values that she espouses to represent,” Barnes continued, noting that Gabbard was one of the last House Democrats to support an impeachment inquiry against Trump. “Coming out against impeachment? Come on. Is she really going to stand up onstage and say that? I can only imagine that that is an invitation for 100 percent of the participants just to cut her off at the knees."

Gabbard said last week that she supported an impeachment inquiry after reviewing Trump’s comments and actions regarding Ukraine. But she has remained critical of other Democrats’ rhetoric on impeachment — especially of impeachment references in fundraising emails sent by a number of other candidates.

Those Democrats are “further dividing our already fractured country,” Gabbard tweeted. “Please stop.”

Strategists and operatives on other campaigns refused to speculate on the record about who Gabbard could criticize during this debate — or how. But privately, top officials on multiple campaigns said Warren, Harris, Cory Booker, Amy Klobuchar or Pete Buttigieg could end up tangling with Gabbard.

Others thought Gabbard could draw a contrast with Biden, although Gabbard has previously defended the former vice president against criticism from Harris. The two spent time talking together onstage after the last debate in which Gabbard participated. But Gabbard’s contrast with Biden’s long record on foreign policy is among the starkest policy differences in the wide Democratic primary field.

"I would watch for Tulsi to be one of the wild cards that blows up the debate," a veteran Democratic presidential campaign strategist said. "If I were preparing for this debate with one of the other candidates, especially if I was Elizabeth Warren, I would be very wary of Tulsi Gabbard now being back on the stage.”

Kurt Ehrenberg, a veteran New Hampshire Democratic strategist and former Sanders adviser, suggested there was at least one candidate with nothing to fear from Gabbard’s sharp debating style on Oct. 15. Gabbard was one of the few elected officials who backed Sanders in 2016, and the Vermont senator and the Hawaii House member have more in common ideologically than most of the rest of the field.

“If she beats up on a kindred spirit people will just get angry at her,” Ehrenberg said. Instead, he offered: “Be a hero to the left.”