Ronald Reagan's Maryland campaign organization yesterday released telephone survey showing the Republican presidential contender narrowly leading President Carter in suburban Washington and nearby Anne Arundel County, but suffering from suprisingly soft support among Republicans and in conservative areas considered essential to carrying the state.

The figures released yesterday, like canvassing results prepared by Reagan's supporters late last month, also showed that a large number of voters still are undecided or hesitant about their choice, including half of all Democrats. Regan campaign chairman Donald Devine and Republican party officials said this huge undecided block, in addition to Regan's 27 to 21 percent overall lead among voters who named a choice, proved that Maryland's 10 traditionally Democratic electoral votes were well within reach with the election three weeks away.

Carter's Maryland supporters quicklly discounted the survey as unprofessional and misleading, but the results also gave them reason for optimism.

Reagan's support in Baltimore County, according to the survey, does not match that of 1976 Republican candidate Gerald Ford, who lost Maryland but kept the race close by winning the populous county with a margin of 25,000 votes. Calls to around 1,000 voters in Baltimore County by the GOP showed Reagan trailing Carter by 24 to 18 percent, with 58 percent still undecided or supporting independent John B. Anderson. Anderson's support measured only five percent in the overall survey.

Devine was so concerned about the Baltimore County figures that he called a meeting of campaign coordinators yesterday to regroup the county's field campaign. The problem; he said, was that voters who supported moderate Republicans like Ford and GOP vice-presidential candidate George Bush; were still uneasy about Reagan. "George Bush had a lot of support up there that we still need to consolidate," Devine said. "We're working on it but we still have a ways to go."

The Regan campaign, which compiled its figures from 25,880 calls in the last month to registered voters in the Washington suburbs, Baltimore and Anne Arundel counties and some rural areas, included no results from Baltimore City, the Democratic stronghold where Carter won by a 2-to-1 margin in 1976. However, Devine said that each response from Democratic voters in other areas was counted three times to reflect the voter registration edge held by the Democratic party statewide.

In the 13 counties of the First Congressional District, which Ford also carried over Carter in 1976, the survey showed Reagan leading by 35 to 27 percent, a larger lead than Ford held, with 35 percent undecided -- but two other new polls in these 13 largely rural counties in southern Maryland and the Eastern Shore indicated that the Republicans may be doing worse than their own survey showed.

A poll commissioned by Democratic Congressional candidate Roy Dyson and completed by a Washington pollster showed Reagan leading Carter by only 40 to 38 percent, with 16 percent undecided, according to sources in the Dyson campaign.

Both Dyson's poll and one commissioned by the embattled incumbent Republican Congressman, Robert E. Bauman, showed that the Republicans are unlikely to be helped by Bauman after his confession of a struggle with "twin compulsions" of alcoholism and homo-sexual tendencies.

Bauman's own poll, taken last week by the New York firm of Arthur J. Finklestein Associates, showed the prominent conservative trailing Dyson by six points in the aftermath of the revelations, which followed a Justice Department charge that Bauman solicited sex from a 16-year-old boy in the District of Columbia last March. Sources said the poll also showed a high number of undecided voters, although exact numbers could not be learned. Dyson's poll, meanwhile, showed him leading Bauman by 48 to 34 percent.