Republican presidential hopefuls Rick Perry and Rick Santorum may be kicked off the Illinois primary ballot.

Texas Gov. Perry and former Sen. Santorum (R-Pa.) face official challenges to their candidacy petitions for the March 20 primary due to mistakes in their filings that were discovered last week.

Perry may not have followed state laws when he listed a post office box in Austin, Texas, as his address. Illinois law requires candidates to list their home address and not a post office box on the official filing, the Chicago Sun-Times reported.

Santorum failed to file any signatures in four Illinois districts. Additionally, he submitted “far fewer” than the 600 required signatures in 10 other districts, the Chicago Sun-Times reported.

Other presidential hopefuls including Mitt Romney, Ron Paul, Newt Gingrich and Buddy Roemer successfully filed the required 3,000 signatures to qualify for the Illinois ballot.

Former Utah Gov. Jon Huntsman, who dropped out of the race Monday, did not gather signatures in Illinois and decided to skip the primary altogether.

Perry and Santorum experienced similar troubles in Virginia — a more critical swing state for the general election — where they failed to qualify for the March 6 primary because they didn’t submit enough signatures.

Gingrich and Huntsman also failed to qualify in Virginia.

Perry’s campaign filed a lawsuit on the Virginia ballot and was joined by the three other candidates. However, a federal judge ruled against them Friday, declining to put their names on the ballot.

Republican voters in 10 states across the country will go to the polls on March 6, dubbed “Super Tuesday.” The Illinois primary will take place two weeks later on March 20.