President Trump is scheduled to lead a rally in Phoenix tonight, where he is expected to lay into Arizona Sen. Jeff Flake, who has just published a book criticizing the president. There is also speculation that Trump will use the rally to announce a presidential pardon of former Maricopa County Sheriff Joe Arpaio, which he hinted at last week.

Arpaio was convicted last month of criminal contempt of court after “defying a court order to stop detaining suspected undocumented immigrants”; he has not yet been sentenced but the conviction could get him up to six months in jail.

Last Monday, as Trump was dealing with blowback for his lukewarm denunciation of the violent white supremacists in Charlottesville, he told Fox News that he was “seriously considering” pardoning Arpaio, calling the sheriff a “great American patriot.” Speaking to Newsmax later that day, Arpaio sounded hopeful that Trump would follow through, saying that when Trump “says he’s going to do something, he does it.” However, Arpaio seems to have settled into a more realistic view of Trump’s reliability, telling NBC News last night that he doesn’t know if Trump will pardon him in Phoenix.

A coalition of civil rights organizations, including People For the American Way, wrote to Trump today urging him not to pardon Arpaio, noting:

During his 24 year tenure as a sheriff in Arizona, Joe Arpaio used his position of authority to drive a personal agenda of hate and racism through a brutal assault on Maricopa County’s Latino population. In the name of cracking down on undocumented immigrants, Arpaio brutalized and terrorized thousands of Latinos. His tactics included racial profiling of children, tourists, legal residents, and U.S. citizens – often detaining them for hours at a time without a criminal charge or warrant. He inflicted inhumane punishments that involved torture, humiliation, and degradation of Latino inmates.

As we wrote last month, Arpaio’s notorious racial profiling of Latinos in his county is only part of his record of extremism, which includes birtherism and staging an assassination attempt:

Arpaio is a hero to the anti-immigrant movement thanks to his inhumane treatment of Latinos and a hero to the racist birther movement thanks to his refusal to give up the cause. (Never mind that his “cold case posse” was one big grift on behalf of the birther website WorldNetDaily.) If Trump chooses to pardon Arpaio—and especially if he announces it at a big, campaign-style rally—it will send yet another signal to the most extreme elements of his base that he is not abandoning their priorities.