Former U.S. Ambassador to the UN Nikki Haley called President Trump's Friday tweet referencing a robbery at House Oversight Chairman Elijah Cummings' Baltimore home "so unnecessary" in a Twitter response.

Why it matters: Haley is the rare top former Trump administration official who left both on her own terms and in the president's good graces. Additionally, because she is often viewed as a potential GOP presidential contender in the future, her decision to directly respond to Trump — complete with an eye roll emoji — is significant in a party that often chooses not to do so.

White House counselor Kellyanne Conway jumped into the fray on her boss' behalf later Friday, quote tweeting Haley's response and responding: "THIS is so unnecessary ... Trump-PENCE2020"

The backdrop: Trump tweeted this morning, "Really bad news! The Baltimore house of Elijah Cummings was robbed. Too bad!"

A break-in was reported at Cummings' home early Saturday morning, per CBS Baltimore — hours before Trump unleashed a barrage of Twitter attacks against the senior House Democrat. It's yet not known if anything was taken.

On Saturday morning, Trump called Cummings' majority-black district a "disgusting, rat and rodent infested mess," the latest in a series of attacks against congresspeople of color who directly oppose the president's agenda.

As head of House Oversight, Cummings has been a leading Trump critic, issuing subpoenas against top administration officials in the process and blasting the state of Border Patrol facilities at the southern border.

Go deeper: Trump plants racial explosives in the urban-rural divide