In a lengthy Twitter thread, Omar contended that pushing racial justice and standing behind "Black Lives Matter," whose activists have advocated "defunding" the police, was a boon to the party's electoral prospects.
"When people single out a slogan like 'Defund' as a catch-all excuse for underperformance, they are undermining a movement of Black activists who stared down police repression as they demanded change in the streets," she said.
"They're also playing into the Republican efforts to distort the success and popularity of the movement. It is the job of activists to gain attention for their cause. It is the job of elected officials to translate those cries for justice into popular legislation."
The tweet seemed to represent a second indirect attack on Rep. Abigail Spanberger, D-Va., who caught attention for her animated response to the party's leftward drift before November.
During a caucus call just days after the election, Spanberger told her colleagues: “We lost races we shouldn’t have lost. Defund the police almost cost me my race because of an attack ad. Don’t say socialism ever again. We need to get back to basics.”
House Majority Whip Jim Clyburn, D-S.C., similarly said if “we are going to run on Medicare for All, defund the police, socialized medicine, we're not going to win," his office confirmed.
At a rally Thursday, Omar balked at the "basics" argument. "So, I was confused because I thought what is more basic than fighting for clean water? What is more basic than fighting for a breathable planet? What is more basic than trying to make sure we get health care for people?" she asked, before adding a litany of other causes.
Omar's comments came at an event promoting the Green New Deal, an ambitious climate reform plan that has increasingly been held up as evidence of Democrats' swerve to the left. Along with Omar, fellow "Squad" members Rep. Alexandria Ocasio-Cortez, D-N.Y., and congressman-elect Mondaire Jones, D-N.Y., spoke at the event as well.
After her Friday thread, Omar joined Ocasio-Cortez in condemning the Biden team's reported consideration of Rahm Emanuel, a former Obama administration adviser, mayor of Chicago and Democratic mainstay, for a spot in the next administration.
The two retweeted a post in which Jones accused Emanuel of covering up Laquan McDonald's murder. "That he's being considered for a cabinet position is completely outrageous and, honestly, very hurtful," Jones added.
McDonald was fatally shot by a Chicago police officer in 2014. The officer was eventually found guilty of second-degree murder.
In separate tweets, Jones accused Emanuel of trying to "weaken" the Affordable Care Act (ACA), and attacked him for school and clinic closures that impacted the Black community.
"I believe the Biden Administration is sincerely committed to dismantling systemic racism," Jones tweeted. "Giving Rahm Emanuel a cabinet position would threaten that vital work," he added, alongside a link to an online petition opposing Emanuel's appointment.
Emanuel has defended his handling of the McDonald case, denying in a 2015 op-ed that he withheld video of the shooting because of an election.
He added: "No one could have predicted that it would take more than a year to finish the probe ... At the end of the day, I am the mayor and I own it. I take responsibility for what happened and I will fix it."
Emanuel's brother Dr. Ezekiel Emanuel has already joined Biden's transition team. He is an oncologist who works with the National Institutes of Health and served as an Obama administration advisor from 2009 to 2011
Ocasio-Cortez previously said Emanuel would be a "divisive" pick and jabbed him when news surfaced that he was joining a Wall Street firm after serving as Chicago's mayor.
"Not all Democrats are the same," she tweeted last summer.
Amid what appeared to be a deepening rift within the party, Biden transition official Jen Psaki seemed to make an effort at assuaging progressives' fears. “I would encourage people to wait until we've made even one announcement about a Cabinet member and certainly more than just a dozen White House names, before they pass judgment," she said.
She also claimed that Biden's cabinet would have "people from diverse backgrounds, diverse experiences, and a diversity of political views, including from all sides of the Democratic Party.”
Ocasio-Cortez recently told The New York Times that the Biden team had a thin line to walk in appeasing the party. Picking Emanuel, she said, would signal "a hostile approach to the grass-roots and the progressive wing of the party.”
She added that she didn't "envy the Biden team. It’s a very delicate balance. But I think it’s really important to strike a good one. Because it sends a very, very powerful message on the intention to govern.”
Fox News' Paul Steinhauser and Madeleine Rivera contributed to this report.