MEXICO CITY (AP) — A court document says U.S. agents have evidence that drug cartel leaders paid millions to the governor of a Mexican border state and other members of the country's former ruling party to gain political influence.A 13-page DEA complaint filed in a Texas federal court says four informants reported that the leaders of the Gulf and Zetas cartels paid members of the Institutional Revolutionary Party including Tomas Yarrington, who served as governor of Tamaulipas state in 1999-2004. The DEA says a ledger it obtained supports the allegations.The investigation could have ramifications for Mexico's presidential race. The candidate of the Institutional Revolutionary Party has a big lead in opinion polls heading toward the July election.