The landslide victory of Spanish Prime Minister-elect Mariano Rajoy failed to quiet Spain's economic turmoil Monday.

The country's borrowing costs edged closer to the 7 percent interest rate at which Greece, Ireland and Portugal needed to secure international bailouts, while a key Madrid stock index slid more than 3 percent.

Some analysts said Mr. Rajoy needs to move quickly to lay out his plan for austerity measures to cut the country's debt and avoid the need for a bailout. But he said in his victory speech Sunday, “There won't be any miracles. We never promised any.” His People's Party said no additional statement was planned Monday.

The 56-year-old Rajoy will not take over the Spanish government until December 20. As the country's unemployment rate topped more than 20 percent, angry Spanish voters ousted the governing Socialists.

The election handed Mr. Rajoy's center-right People's Party 186 seats in the 350-member lower chamber of Parliament, the country's biggest electoral sweep in 30 years. The Socialists dropped from 169 seats to 110, their worst performance ever.