Arizona Sheriff Joe Arpaio is one of the most controversial law enforcement officers in the United States. Now, his days may be numbered — thanks in part to an immigrant-led movement to oust him.

The strength of the movement was evident recently in a Phoenix parking lot, where about 500 volunteers gathered to knock on doors and persuade voters to oppose the Maricopa County sheriff. Organizers call this the biggest canvass to date against the sheriff, who has been in office nearly 24 years and is running in a tough re-election race.

Arpaio is not just a local sheriff. He has earned friends and foes across the country for his push against illegal immigration and his ties to Republican nominee Donald Trump. At one point, Arpaio’s office conducted immigration patrols and worksite raids, though US federal courts have since suspended those tactics.

People are traveling from all over to help block "Sheriff Joe" from re-election. The campaign calls itself “Bazta Arpaio,” a play off the Spanish word for “enough,” spelled with a "z" to include the abbreviation for Arizona. “We have people who came from New York, from Atlanta. We have people from New Orleans, from Kentucky," says Abril Gallardo, a Bazta Arpaio organizer.

Maricopa County Sheriff Joe Arpaio listens to US Republican presidential candidate Donald Trump speak at a campaign rally in Marshalltown, Iowa January 26, 2016. Arpaio endorsed Trump at the rally.

Brian Snyder/Reuters

Three years ago, a federal judge found Arpaio’s immigration enforcement tactics racially profiled Latinos. Now, the sheriff faces criminal contempt of court charges for disobeying the judge in that case and continuing to make immigration arrests after he was ordered to stop. The formal criminal contempt charge was filed against the sheriff on Oct. 25. If convicted, he could face a maximum of six months in prison.

More: What you need to know about the criminal case against Sheriff Joe Arpaio

All of this motivates his opponents. Many are immigrants themselves. They wear matching black Bazta Arpaio T-shirts. Giant balloons depicting Arpaio in prison stripes and Trump in a KKK outfit are propped up adjacent to a stage where speakers fire up the crowd.

“Joe Arpaio is done,” a woman shouts into a microphone. “He's already lost. He's on his way down. What our opportunity is [is] to be the ones to knock him out.”

She continues: "The people who he’s picked on, the people he's abused, the people he’s talked about, the people he's demonized, we will be the people that take him out of office once and for all this November.”

Also: 'Detained because my name was Gonzalez'

Later that day, three women knock on doors in the Phoenix suburb of Chandler. Only one of the three is a citizen and able to vote herself. Their list includes minority and millennial voters who may need an extra nudge toward the polls. The canvassers do not actively promote Arpaio’s opponent, Democrat Paul Penzone. Instead, they pass out anti-Arpaio literature with a cartoon of him with Trump and a line through them both.

Sheriff Joe Arpaio's opponents rally in front of the federal courthouse after US Justice Department lawyers announced on Tuesday, Oct. 11, 2016, that they will bring criminal contempt of court charges against the sheriff.

Jude Joffe-Block/KJZZ

“Brewer hit a sore spot,” Renteria says in Spanish. She hopes Brewer's remarks will compel Latinos to prove the former governor wrong.

Down the street, the group of canvassers meet a Latina voter named Marcela Santos, who says she has already mailed in her vote against Arpaio. “Just because he is against the immigrants and deporting people and innocent people who just want to be here working, have a better life,” Santos says.

The anti-Arpaio movement does not worry Chad Willems, Arpaio’s campaign manager.

“It’s really telling that they had to bring in people from out of state,” Willems says. “They don't have any organic grassroots support here for the people that vote here, that live here.”

Whatever the case, many polls do show Arapio trailing Penzone.

Arpaio has benefited from out-of-state campaign donations and raised $12 million, according to his campaign. The money has meant lots of television ads. One highlights his work protecting animals; another attacks his opponent; another accuses the Department of Justice of unfairly trying to influence the election by announcing intentions to prosecute him for criminal contempt right as early voting began.

Willems says that message is working. “Our fundraising has picked up immensely,” he says. “The number of volunteers we have out knocking on doors and making phone calls has more than doubled.”

Meanwhile, on a recent evening the Bazta Arpaio crew gathers in front of the sheriff’s downtown Phoenix headquarters to throw him a retirement party. At one point, the activists catch a glimpse of Arpaio through a window in his building.

“He’s going down! Arpaio’s going down!” they chant, while joining hands and holding them overhead in a sign of victory.

On Nov. 8, they will find out if county voters agree.

From PRI's The World ©2016 PRI