Todd Axtell had just taken over as St. Paul police chief last summer when immigrant advocates pressed him on a longtime grievance: The department has refused to back most applications for special visas that allow crime victims who help police to stay in the country.

The advocates wanted to know: Why can't St. Paul's department act more like Minneapolis police?

A law enforcement agency must confirm that immigrants were crime victims and cooperated with police before they can petition the federal government for "U visas," which open a path to citizenship. Minneapolis police have backed more than 80 percent of the visa applicants in recent years, putting it near the top nationally.

St. Paul's rate, by contrast, has hovered around 10 percent. Some Twin Cities suburbs approve an even smaller share.

The Trump administration's tougher stance on immigration enforcement has fueled a push to lobby police on the issue and to promote legislation that would compel a more consistent approach across Minnesota law enforcement agencies.

"It's unfortunate that if you are a victim on this side of the river, you will be denied, but on the other side your request will be signed," said John Keller of the St. Paul-based Immigrant Law Center of Minnesota.

With U visa applications climbing nationally, the program's critics — from Congress members to some law enforcement officials — have become more vocal, saying some immigrants abuse the program.

Congress created the U visa program in 2000 with bipartisan support to encourage crime reporting and cooperation by immigrants who otherwise might fear that contacting police would get them deported. Applications for the visas have gone up almost sixfold since 2010. The increase, coupled with an annual limit on the visas, has led to a backlog of more than 150,000 petitions nationally.

Local cops have broad discretion in handling the visa applications, which has resulted in significant differences across police agencies. Some departments sign requests only if an investigation is underway, while others do so only after a case has been closed, or even refrain from participating, said Ian Bratlie, who works on racial justice issues with the American Civil Liberties Union of Minnesota.

Minneapolis and St. Paul each saw marked increases in visa certification requests this winter, and the way they handled them has differed substantially in recent years.

A Star Tribune analysis found that the Minneapolis Police Department approved about three of four such requests since 2014. A Reuters analysis found several years ago that the agency ranked fourth nationally, surpassing departments in much larger cities and with higher crime rates.

"The department has done a good job messaging to immigrant communities that we want them to call us and we are here to serve them," said Cmdr. Eric Fors, who reviews certification requests.

In the past three years, the department received more than 2,000 U visa certification requests, compared with a total of about 240 in St. Paul.

Gloria Velazquez said she was reluctant to apply for a visa after two men robbed her in Minneapolis in 2012. She had been deported previously, and she feared run-ins with law enforcement. Velazquez said she was pleasantly surprised when her request was approved after just four days, shifting her view of local police.

Robbery is not on a federal government list of crimes that qualify victims for a U visa, but Minneapolis police have chosen to approve requests from robbery victims, citing wide discretion under the law.

St. Paul police began taking a more restrictive view of U visa applications in the fall of 2013, and its approvals plummeted and remain about 10 percent. A panel of three officers had started reviewing the applications and they were reluctant to sign off on requests involving less serious crimes and long-closed investigations, said Keller of the Immigrant Law Center.

"They said they wanted to stop being a rubber stamp," Keller said.

St. Paul did approve more than 60 percent of requests involving domestic assault victims. The St. Paul-based advocacy group Casa de Esperanza gives the department high marks for that, saying U visas are crucial for victims who fear they will be deported and separated from their children if they report their abusers.

Immigrant lawyers like Danielle Robinson Briand, however, contend that St. Paul has hindered its efforts to improve immigrant relations overall. She said her colleagues have been known to quip that they had a great U-visa case — "except for the fact that it happened in St. Paul."

Critics want more scrutiny of U visa applications. Top congressional Republicans wrote the outgoing Department of Homeland Security secretary in December to caution that the program "is being exploited by those wishing to defraud the system and avoid deportation."

West St. Paul Police Chief Bud Shaver, whose department has approved just two of 43 requests since 2012, said the program was meant to be a tool to help with police investigations, not "a free pass to stay in the United States." Shaver said his department recently got a certification request after two men reported getting robbed at gunpoint in a parking lot. There was no evidence of the robbery, he said, and they couldn't describe the robber.

"Did they just report something to get a U visa? I don't know," Shaver said. "I have heard that sometimes a crime is invented so someone can apply for a U visa, particularly in places where they sign a lot of requests."

Some immigrant advocates acknowledge such scams take place. A Twin Cities immigration attorney said she is fighting the deportation of an 18-year-old whose underage girlfriend's family had welcomed him for overnight visits. They reported him to police only after they learned that as a victim of statutory rape, the girl and her immediate relatives could get U visas.

Advocates and immigration attorneys say that abuse of the program is rare, however. Fors, the Minneapolis commander, is skeptical that fakers can game the application review process.

"It would be difficult to imagine a 42-year-old woman who works two jobs fabricating being punched in the face during a robbery and suffering substantial injuries to get a visa," he said.

When Axtell took over the St. Paul Police Department last year, U visa advocates brought him studies showing that immigrants in the country illegally are more likely to be victimized and less likely to call police.

Advocates say they were heartened by Axtell's response. The department's certification approval rate has jumped to 25 percent so far this year, and it has agreed to reconsider some previous denials. Cmdr. Ken Sass, who sits on the panel that reviews requests, says the department made the process less subjective by focusing on whether the crime was on the federal list of qualifying offenses and whether the victim was helpful.

Now advocates are turning their attention to suburban and greater Minnesota law enforcement — and to the Legislature.

One bill would give law enforcement 90 days to respond to U visa petitions and require agencies to report approval statistics. The bill also clarifies that agencies should not consider pending investigations, the filing of charges or a conviction a prerequisite for approval. The bill faltered this year, but advocates plan to try again next year.

Sass said St. Paul police would welcome less ambiguous guidelines. "We're cops," he said. "We like rules and regulations."