Some critics of Black Lives Matter use the phrase "all lives matter" as a counter slogan. Black Lives Matter activists oppose America's disproportionate police violence against black people. When Democratic contenders Hillary Clinton and Martin O'Malley said "all lives matter" in 2015 during the last presidential primary race, those comments earned fierce pushback from progressives.
Buttigieg's comments about race and policing, as well as his record on race as mayor, could prove to be another lightning rod as voters seek out more information on Buttigieg, the only candidate polling above 1 percent without ever holding federal office.
Some local activists have for years been critical of Buttigieg's economic policies, which they say have disproportionately benefited white residents while doing little to address a higher unemployment rate among minorities. His critics also say Buttigieg's comments as mayor don't always stack up against his progressive rhetoric as a presidential candidate.
"That's four years ago, but it was not that long ago. It was not a time when 'all lives matter' was a smart thing to say, or reflective of someone who is concerned about black people being killed by the police," said Nate Levin-Aspenson, a local organizer in South Bend.
"What I would say is, take a look at what he is saying now, and compare that to his record as mayor. See what you find," Levin-Aspenson said.
Buttigieg's comments could also put a spotlight on one of the more controversial aspects of his tenure as mayor of South Bend, involving secret recordings allegedly made of South Bend police officers at the direction of the city's first African-American police chief, Darryl Boykins. Buttigieg demoted Boykins, who ultimately obtained a $75,000 settlement from the city after suing over what he described as Buttigieg's "racial animus."
The officers believed to be recorded in the tapes also obtained a settlement from the city, for $500,000.
Buttigieg has maintained that releasing the tapes would violate federal wiretapping laws, and the settlement Boykins reached included a clause that stipulated the city did not admit to any wrongdoing regarding "disputed and doubtful" claims.
But the millennial mayor has noted the effect of the controversy on his standing in the city's minority communities.
"Overwhelming pressure mounted for me to disclose the recordings, especially from the African-American community," Buttigieg wrote in his political memoir released this year. Protesters picketed his first State of the City address, he wrote, and the story "affected my relationship with the African-American community in particular for years to come."
During the 2015 State of the City address, Buttigieg said that he was taking steps to build a more diverse police department and planned to engage the "services of professionals with a proven track record of helping American cities improve diversity and inclusion in their hiring in public safety and beyond."
Race is an increasingly important issue in the Democratic primary process, with more than 80 percent of African-American voters identifying as Democrats. Black voters accounted for nearly a quarter of the Democratic primary electorate in 2016, according to a CNN analysis of exit poll data.
Clinton, eventually the Democratic nominee, came under fire for her use of the phrase "all lives matter" in June 2015 while speaking at a black church near Ferguson, Missouri. The next month, Martin O'Malley, another contender, apologized for his use of the phrase.
Sen. Bernie Sanders, I-Vt., who lost to Clinton in 2016 and is leading the pack of declared Democratic candidates this cycle, also came under scrutiny that summer after appearing to dismiss activists with the Black Lives Matter movement who interrupted one of his events in Arizona.
"Black lives, of course, matter," Sanders said. "I spent 50 years of my life fighting for civil rights and for dignity. But if you don't want me to be here that's okay. I don't want to outscream people."