Former President Barack Obama shared Saturday a Washington Post op-ed by his former staffers, which criticizes President Donald Trump for his treatment of minority groups and for derogatory comments about 4 congresswomen of color.

"We stand with [the] congresswomen ... as well as all those currently under attack by President Trump, along with his supporters and his enablers, who feel deputized to decide who belongs here — and who does not. ... We refuse to sit idly by as racism, sexism, homophobia and xenophobia are wielded by the president and any elected official complicit in the poisoning of our democracy."

— Obama former staffers, Washington Post op-ed

Why it matters: It's unusual for Obama to comment on current politics. Former presidents have traditionally refrained from criticizing successors, regardless of party affiliations.

The op-ed was published the same day as Trump slammed Rep. Elijah Cummings (D-Md.) and called the majority-black Baltimore-area district he represents a "disgusting, rat and rodent infested mess."

The big picture: The op-ed, co-signed by 149 African Americans who served in Obama's administration, addresses Trump's "go back" attacks on Reps. Ilhan Omar (D-Minn.), Alexandria Ocasio-Cortez (D-N.Y.), Rashida Tlaib (D-Mich.) and Ayanna Pressley (D-Mass.):

"Go back where you came from. Go back to Africa. And now, 'send her back.' 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. ...

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

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