MEXICO CITY (AP) — The apparent victor of Mexico's presidential race, Enrique Pena Nieto, struggled Monday with the sticky bonds of his party's notorious past, the limitation of his mandate and an opponent who has yet to concede defeat.

His long-ruling and now-returned Institutional Revolutionary Party, the PRI, won only about 38 percent of the vote and is unlikely to get a majority in Congress. In fact, it may lose seats.

He faces an old guard in the PRI that still exercises considerable power, an ongoing war against fierce drug cartels and a still sluggish economy. His closest rival, leftist Andres Manuel Lopez Obrador, who polled a higher-than-expected vote of about 32 percent, has refused to accept the loss, and many of his militant followers are suspicious of the results.