MOSCOW — The Georgian authorities charged one of President Mikheil Saakashvili’s top political partners with embezzlement and abuse of power on Tuesday, in the new government’s most decisive move yet against Mr. Saakashvili’s pro-Western team, which came to power in the 2003 Rose Revolution and dominated Georgian politics for nine years.

The official, Vano Merabishvili, is head of Mr. Saakashvili’s party, the United National Movement, and for years wielded great power as the head of Georgia’s police and security services and then as prime minister. But he saw his influence dwindle quickly when an opposition coalition, Georgian Dream, won parliamentary elections in 2012.

Among the campaign promises that swept Georgia’s new prime minister, Bidzina Ivanishvili, into office was a pledge to prosecute Saakashvili officials for offenses including corruption and police brutality. Dozens of officials have been charged with crimes since Mr. Ivanishvili’s election, but Western diplomats have urged restraint, especially in cases that involved political rivals like Mr. Merabishvili.

If convicted on the abuse-of-power charges, Mr. Merabishvili could face a prison term of seven to 12 years, prosecutors said. His lawyer, Giorgi Chiviashvili, told Georgian television that he would plead not guilty.