Primary voters in Illinois will go to the polls next Tuesday, but it’s recommended that those voting by mail turn in their ballots by 5 p.m. March 10, which is one week in advance, to make sure their votes are postmarked in time.

The recommendations follow a change made by the U.S. Postal Service under the Trump administration.

The change redefined the meaning of postmark. Under the old system, the postal service postmarked mail when it received it. Now, USPS will postmark mail when it processes it. The change went into effect late last year.

Both major political parties in Illinois are recommending their primary voters send ballots in one week before election day.

Democratic Party Chair Lisa Hernandez; U.S. Rep. Nikki Budzinski, D-Springfield; and Adams County Party Chair Katie Daniels said on Monday that voters should send their ballots by mail at the end of the day Tuesday to ensure their votes can be counted.

“I know that our postal employees are working very hard. I see them out every day, working very hard to get us our mail on time,” Daniels said. “But with these policy changes, it’s really caused an issue with getting postmarks on your ballot.”

Daniels, who represents the county, which includes Quincy, said this is especially important for voters in rural areas, where mail delivery can be even slower.

“By some anecdotal information, we are seeing that in Adams County we are experiencing some really slow mail times, and some days we don’t get mail at all,” Daniels said.

A flyer shared by the Illinois Republican Party says postmark delays can take up to one or two days — and potentially more in rural areas.

If Illinoisans can’t send their mail-in ballots one week before election day, the Democratic Party recommends turning in your ballot at an early voting location or directly to the local election authorities, Hernandez said.

For those who requested a mail-in ballot but still haven’t received it, they should instead plan to vote in-person early or on election day, Hernandez said.

“This postal change has been described as small, but it has the potential to suppress voters, especially voters with disabilities, military, rural voters and elderly voters,” Hernandez said.

USPS also recommends voters send mail-in ballots one week before the deadline for voters’ local election offices.

The Illinois State Board of Election allows mail-in ballots to be counted up to 14 days after election day, so long as the ballot was postmarked by election day.

This rule is being challenged in court by U.S. Rep. Mike Bost, R-Murphysboro, who contends the Illinois law shouldn’t supersede federal law that defines election day.

After lower courts determined Bost lacked legal standing to challenge the state law, the U.S. Supreme Court ruled 7-2 in January that the congressman and two other 2020 primary delegates for President Donald Trump could sue.

The high court’s decision means Bost’s challenge has gone back to the U.S. District Court of Northern Illinois, which is based in Chicago.