MEXICO CITY (Reuters) - Eager to clean up its image before the 2018 presidential election, Mexico's ruling party is weighing whether to discipline two former state governors after expelling another wanted on corruption charges.

Institutional Revolutionary Party (PRI) Senator Arturo Zamora said on Wednesday that the party's justice committee was reviewing whether to act against former governors Roberto Borge from Quintana Roo and Cesar Duarte in Chihuahua, whom the opposition have accused of fraud and corruption.

The governors deny any wrongdoing.

"Proceedings have been initiated, and we don't know what the result of these two cases will be," Zamora said in a radio interview, noting the party was still gathering evidence.

Battered by allegations of graft, misuse of public funds and conflict-of-interest scandals, President Enrique Pena Nieto's PRI has vowed to go after corrupt officials to counter entrenched public skepticism.

On Tuesday, the PRI expelled outgoing Veracruz governor Javier Duarte, who has been missing since the attorney general's office said a week ago it was seeking his arrest on suspicion of involvement in organized crime and money laundering.

Both Borge and Duarte's terms in office ended in the months after the PRI lost control of their states in a string of regional election defeats in June.

Corruption allegations have swirled around several state governors in recent years, but few have led to prosecution.

Pena Nieto himself became embroiled in a conflict-of-interest controversy in late 2014 when it emerged he, his wife and then-finance minister Luis Videgaray had all bought or made use of houses owned by government contractors.

A subsequent investigation ordered by Pena Nieto found no evidence of any wrongdoing by the three, though it was panned as a whitewash by the opposition.

On Tuesday, Pena Nieto said presidents of Mexico do not wake up thinking how to "screw" the country as he sought to defend his record.

Opinion polls show the centrist PRI faces a tough battle to retain power in the next presidential elections, with opposition hopefuls on the left and right setting the early pace.

(Reporting by Dave Graham; editing by Grant McCool)