Evan Vucci, Associated Press
President Barack Obama speaks during a summit on cybersecurity and consumer protection, Friday, Feb. 13, 2015, at Stanford University in Palo Alto, Calif.

RANCHO MIRAGE, Calif. — President Barack Obama has spoken with the leaders of Ukraine and Germany as fighting continued between Ukrainian forces and Russian-backed separatists in eastern Ukraine hours before a scheduled cease-fire.

The White House says Obama and Ukrainian President Petro Poroshenko (por-oh-SHEHN'-koh) on Saturday stressed the need for all sides to halt the violence beginning at midnight in the region as scheduled.

The leaders of Germany, France, Ukraine and Russia agreed to the cease-fire this week after a marathon negotiating in Belarus.

The White House says Obama, Poroshenko and German Chancellor Angela Merkel (AHN'-geh-lah MEHR'-kuhl) all expressed concern about intense fighting in and around the key government-held railway hub of Debaltseve.

Obama also congratulated Poroshenko on securing assistance from the International Monetary Fund to help stabilize the Ukrainian economy.