A Prince George's County legislator, saying widely used exit polls have created "election day media madness" in his District Heights neighborhood and elsewhere in Maryland, proposed today banning such public opinion surveys within 300 feet of polling places.

Exit polls serve "no real or positive purpose," said Del. Dennis C. Donaldson. He added that exit polls -- surveys of voters as they leave polling places that many news organizations and political analysts use to project election winners -- often "distort" election returns.

"There's also voter resentment and annoyance at the media bombarding them with questions and buttonholing them after they vote," Donaldson told the Constitutional and Administrative Law Committee.

But the proposal was quickly criticized by media representatives. Lou Davis, president of the Maryland chapter of Sigma Delta Chi, a society of professional journalists, branded the bill "unconstitutional. An exit poll is a tool we use to gather information, a right protected by the First Amendment. To ban the exit poll would limit that ability and that right."

Donaldson, a Democrat, said his proposal was inspired by an informal complaint from a Republican election judge in Prince George's County, who witnessed a national network television crew enter a polling place last November to question a voter. The judge complained to Donaldson that the questioning was unfair to voters.

Donaldson's proposal, which is similar to one scheduled for a hearing in a Senate committee on Wednesday, is modeled on a 1983 Washington state law that bans any "exit poll or public opinion poll with voters" within 300 feet of a public polling place.

The Washington law has survived a legal challenge by the three major television networks, The New York Times and The Everett Herald, a newspaper owned by The Washington Post Co. The case is still before the federal district court in Tacoma, Wash.

Today's hearing on Donaldson's bill came less than one week after the three major television networks agreed not to use exit polls to project the probable presidential election winner in any state until that state's polls have closed.

Some observers believe that the Jan. 17 agreement, which followed public criticism and pressure arising from early projections last fall and in 1980, opens the way to a uniform poll closing time for presidential elections in the contiguous 48 states.

Davis, in explaining journalists' objections, said "The problem with exit polls comes in the broadcast of the results before polls close -- and I know for sure that nobody in Maryland has done that."

"Exit polling is a legitmate way for the news media to gauge the results of an election before the results become widely known," said Davis, the bureau chief here for WMAR-TV, the NBC affiliate in Baltimore. Like its competitors, WMAR conducted exit polls during the 1984 presidential election.

Donaldson's bill has the backing of the League of Women Voters and may enjoy broad support in the General Assembly, some of whose members are on less than warm terms with reporters covering the session.

As State Elections Administrator Marie Garber put it today during her testimony on Donaldson's bill: "Most politicians, most candidates would prefer not to have it known how the election is going."