WASHINGTON, July 8 - The U.S. Department of Justice has sent letters to all 50 U.S. states warning that election officials could face criminal charges for allowing noncitizens to remain on their lists of eligible voters.

The letters, sent on Tuesday, are the latest attempt by Republican President Donald Trump’s administration to pressure states ahead of November’s midterm elections, which will decide control of Congress.

The letters, sent by Harmeet Dhillon, the head of the Justice Department’s Civil Rights Division, warn that state election officials can be charged under several federal laws designed to safeguard U.S. elections and bar noncitizens from casting ballots.

“Any election officer, including the chief election officer of the state, who knowingly retains noncitizens on the state’s SVRL (state voter registration list) or facilitates noncitizens in receiving and casting ballots could be subject to criminal liability,” Dhillon wrote in one letter, which was seen by Reuters.

The Trump administration has attempted a series of maneuvers  to take greater control of elections, which are administered by states under the U.S. Constitution. Trump and his allies have long claimed that people living illegally in the United States pose a threat to election security, though several studies have found that voting by non-U.S. citizens is rare.

The Trump Justice Department has lost a series of lawsuits seeking to obtain nonpublic voter data from states as part of what the DOJ has described as an effort to ensure ineligible voters do not remain on voter rolls.

The letters from Dhillon show the DOJ’s interest in elevating the issue despite its courtroom setbacks and warn of potential criminal charges against election officials ahead of hotly contested congressional elections.

"The Department sent these letters to all 50 states and the District of Columbia, asking for voluntary compliance in a timely manner with their obligations under federal law to ensure only citizens vote in federal elections,” a Justice Department spokesperson said in a statement.