Former President Barack Obama highlighted on Twitter Saturday an article written by former members of his administration that sharply rebukes racism in American politics and takes aim at recent racist comments by President Donald Trump.

The op-ed was published in the Washington Post Friday and co-signed by more than 140 African Americans who served the Obama administration who wrote that the "racism surge" in the country "provided jet-fuel for our activism."

Obama's tweet came hours after Trump attacked Rep. Elijah Cummings and Baltimore as a defense of conditions in immigration detention centers at the southern border.

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Former President Barack Obama promoted an article that sharply rebukes racism in American politics and takes aim at recent racist comments by President Donald Trump.

In a Saturday tweet, Obama linked to a Washington Post op-ed that was co-signed by more than 140 African Americans who served the Obama administration.

"I've always been proud of what this team accomplished during my administration," Obama wrote above the article. "But more than what we did, I'm proud of how they're continuing to fight for an America that's better."

Read more: 'We are patriots': More than 140 African American who worked in the Obama administration write an op-ed calling for end to discrimination in the US

The op-ed was published on Friday and written by Clarence J. Fluker, C. Kinder, Jesse Moore, and Khalilah M. Harris. Listed as a signatory is Valerie Jarrett, a friend and former senior advisor to Obama.

"Witnessing racism surge in our country, both during and after Obama's service and ours, has been a shattering reality, to say the least," they wrote. "But it has also provided jet-fuel for our activism, especially in moments such as these."

Obama's tweet came hours after Trump attacked Rep. Elijah Cummings and the district of Baltimore on Twitter, seemingly echoing comments on a "Fox & Friends" episode that compared the city of Baltimore to the conditions in detention centers at the southern US border.

Then, Trump tweeted "Why is so much money sent to the Elijah Cummings district when it is considered the worst run and most dangerous anywhere in the United States. No human being would want to live there. Where is all this money going? How much is stolen? Investigate this corrupt mess immediately!"

Read more: Trump attacks Rep. Elijah Cummings and Baltimore, seemingly quoting 'Fox & Friends' segment: 'No human being would want to live there'

The authors and co-signers said they specifically stood with Reps. Ilhan Omar, Alexandria Ocasio-Cortez, Ayanna Pressley. and Rashida Tlaib, as they have experienced being told to "go back to where you came from."

"Black and brown people in America don't hear these chants in a vacuum; for many of us, we've felt their full force being shouted in our faces, whispered behind our backs, scrawled across lockers, or hurled at us online," they wrote. "They are part of a pattern in our country designed to denigrate us as well as keep us separate and afraid."

Trump tweeted on July 14 that Democratic representatives Alexandria Ocasio-Cortez, Rashida Tlaib, Ayanna Pressley, and Ilhan Omar should "go back" to their "broken and crime-infested countries," though three out of four of them were born in the US, and all four are US citizens and elected representatives.

Trump rejected criticism of the tweets two days later, saying he doesn't have a "racist bone" in his body. Ocasio-Cortez hit back in a tweet that said, "You're right, Mr. President — you don't have a racist bone in your body. You have a racist mind in your head, and a racist heart in your chest."

The tweets then resurfaced at a North Carolina Trump rally later in the week when supporters chanted "Send her back."

Trump initially disavowed the chants, stating he wasn't "happy" about them and falsely claimed he attempted to stop the chants, despite video evidence showing that wasn't the case. The next day, Trump reversed his position, saying they are "incredible people... those are incredible patriots."

The op-ed's co-signers wrote that such comments are only "jet-fuel for our activism," which would continue for a better future.

"Expect to hear more from us," the op-ed concluded. "We plan to leave this country better than we found it. This is our home."