Prince George's County Councilman Francis B. Francois was elected today as president of the National Association of Counties, the nation's only lobbying and policymaking group for county governments.

In his new positon, Francois will oversee an organization that has grown from a loose association of individual county officials in 1935 to one that now represents 1,800 of the 3,104 county governments in the United States.

The NACO budget is $2 million annually, but the group's presidents are paid expenses only.

Under his administration, Francois said NACO's "No.1 priority" will be lobbying for a reenactment of the $6.85 billion federal revenue sharing program, due to expire Sept.30, 1980.

"The counties were largely responsible for that program and they were great beneficiaries of it," he said. Roughly, counties have received about $2 billion in revenue sharing funds since the program's enactment in 1972.

"I feel very strongly that the concept of revenue sharing is a valid one and one that ought to be made a permanent concept of the American government," Francois said.

Annual NACO lobbying policies are decided upon at the group's yearly conferences, such as the one ending here Wednesday. Success in pushing the lobbyingplatform through Congress could affect the flow of federal dollars to county governments.