PHOENIX (Reuters) - Embattled Arizona lawman Joe Arpaio, whose get-tough policies to fight illegal immigration and praise of Republican presidential candidate Donald Trump brought him nationwide attention, trails his opponent in this year’s election by nearly 15 percentage points, according to a Thursday poll.

Arizona Sheriff Joe Arpaio holds up his flip phone before Republican presidential nominee Donald Trump speaks at a campaign rally in Phoenix, Arizona, U.S., August 31, 2016. REUTERS/Carlo Allegri

The poll, conducted by The Arizona Republic/Morrison/Cronkite News, shows Democratic challenger Paul Penzone has the support of nearly 45.9 percent of those surveyed as he attempts to unseat the six-term Maricopa County sheriff. Arpaio garnered 31.1 percent.

Roughly one-fifth of those surveyed said they were still undecided on the Nov. 8 race for the top law enforcement job in the state’s most populous county. The poll’s margin of error was plus or minus 5.6 percent.

The poll was taken as federal prosecutors announced that the U.S. Justice Department would seek a criminal contempt charge against Arpaio for violating a court order in a 2007 racial profiling case.

The charges center on unlawful traffic stops and detentions by deputies of Latino drivers for 18 months after the judge ordered them to cease.

Arpaio, who has denied any intentional wrongdoing, has already been cited for civil contempt stemming from his actions in the case.

Political observers have said prospects of a criminal prosecution for the 84-year-old hardline sheriff seem to have raised the ante in recent days in what already promised to be Arpaio’s sternest election test.

Arpaio campaign manager Chad Willems disputed the poll results, saying that the campaign’s own survey has the sheriff leading Penzone by 7.5 points.

“The recent ‘poll’ by the Arizona Republic is a complete joke,” said Willems in a statement to Reuters, adding that Democrats were disproportionately included in the survey’s sample size.

“The numbers in NO way accurately depict the electorate of Maricopa County, Arizona,” he said. “Why they chose to conduct their survey this way is beyond any comprehension.”

A Penzone campaign official could not immediately be reached for comment.

Arpaio has continued to play on a national stage during his tenure as sheriff despite his legal battles. His calls for a crackdown on undocumented immigrants, opening a tent city to house inmates and making them wear pink underwear all have proved popular.

He also has appeared for Trump, praising the Republican nominee’s border policies, including building a wall along the U.S.-Mexican border.