The Justice Department on Friday said it will send election monitors to 86 jurisdictions in 27 states on Tuesday, the most in two decades amid growing fears of improper partisan influence and voter suppression.

The announcement comes as officials in some Republican-led states have warned they might attempt to ban federal authorities from entering polling sites on Election Day. They have cast such oversight as partisan, even though Democratic and Republican administrations have monitored elections for potential voting rights irregularities for decades.

The number of jurisdictions subject to in-person federal scrutiny this year represents a 49 percent increase from 2020. It matches the total in 2004, the first presidential election cycle after the Supreme Court helped decide the fiercely disputed 2000 contest between George W. Bush and Al Gore.

All seven of the nation’s most closely contested swing states are represented on the list, with monitors planning to visit six counties in Michigan, five in Georgia, four in Wisconsin and Arizona, three in Pennsylvania and North Carolina, and one in Nevada.

Monitors also will be present in a mix of red and blue states, including California, Florida, Maryland, Missouri, Ohio and Virginia. Texas and Massachusetts have the most jurisdictions on the list with eight apiece.

In 2022, Republican leaders in Missouri and Florida banned federal monitors from entering voting locations. The Washington Post reported this week that officials in those two states said their position that state laws do not explicitly permit federal monitors has not changed.

GOP officials in other states, including Texas, also said in recent interviews that federal monitors could be prevented from going inside polling sites.

Former federal officials said monitors aim to be as unobtrusive as possible, raising any concerns about potential election law violations with local officials and reporting broader observations about election operations to U.S. attorney’s offices and the Justice Department’s civil rights division.

“I do think it’s very promising and very much needed that the number of jurisdictions [being monitored] has increased,” said Katherine Culliton-González, a former Justice Department voting rights lawyer who now serves as chief policy counsel at Citizens for Responsibility and Ethics in Washington.

Monitors “go to places where there is a potential for problems,” she said. “Normally, monitors have a very calming effect.”

Since the Voting Rights Act of 1965, the Justice Department has dispatched government officials into polling sites to ensure fair ballot access for vulnerable populations — including racial minorities, disabled people and those with limited English-language ability — and protect against unlawful partisan influence.

Jurisdictions where monitors will be sent are selected based on factors that include requests from local officials, federal court settlements and areas with fast-changing demographics.

Legal experts said the federal government lost significant legal recourse in 2013, when the Supreme Court struck down key provisions of the 1965 Voting Rights Act. The court eliminated the federal government’s preclearance authority, which required nine states and dozens of counties with a history of voter discrimination, mostly in the South, to request permission to change voting regulations.

The ruling also meant the Justice Department needed a court order or the express cooperation from state and local officials to enter polling sites. The number of federal monitors dropped significantly in the ensuing election cycles.