The Federal Election Commission is looking into four campaign donations Rep. Steve Stockman (R-TX) received possibly relating to the Texas congressman introducing legislation that would give gaming rights to an Indian tribe in the southeastern part of Texas.

Stockman is running in the Republican primary against Sen. John Cornyn (R-TX).

According to the Associated Press on Thursday, the FEC is investigating four campaign donations Stockman received after introducing a bill that would give gaming rights to the Alabama-Coushatta tribe. Those donations, in April and July, came after Stockman introduced legislation giving the Indian tribe rights to open a casino in southeastern Texas.

Two of the donations from a resident of Arizona totaled $5,100 and the other two donations, from an American Indian group in California, totaled $5,000. Stockman introduced the bill in March. According to the Associated Press, the donors cited Stockman’s backing of the casino in their donations.

On Dec. 20 the FEC sent Stockman a letter about the “excessive donations” according to the Houston Chronicle. In that letter the FEC said Stockman had to either refund half of the money he received or “revise its accountings within 60 days of receiving the donations.”

Stockman’s campaign and office did not immediately respond to repeated inquiries by the Associated Press and Chronicle. A Stockman spokesperson did not immediately respond to a request for comment from TPM on Friday either.