BUENOS AIRES, Argentina – Paraguay’s long-dominant ruling party Monday confirmed a former Cabinet minister would be its candidate in the coming presidential election, although her nomination faced a court challenge.

If elected in the April balloting, Blanca Ovelar would become the country’s first female head of state and the third woman elected president in South America in recent years. Women now lead Argentina and Chile.

However, her chief rival for the nomination, former Vice President Luis Castiglione, vowed to pursue his legal challenge.

If her candidacy withstands the internal test, Ovelar probably would confront a pair of popular opposition leaders who have declared their intention to challenge the Colorado Party’s hegemony in the general elections, scheduled for April 20.

The upcoming balloting in a nation long controlled by infamous former strongman Alfredo Stroessner is shaping up as among the most competitive in the country’s history.

Paraguay, a landlocked tropical nation of almost 7 million people in an area nearly the size of California, is a close U.S. ally. The current president, Nicanor Duarte Frutos, must step down this year because of a limit to one five-year term.

The Colorado Party has held sway in Paraguay since 1947, including the 35-year reign of Stroessner, who was ousted by a coup in 1989.