The voters in the 1st Congressional District on Maryland's Eastern Shore may have to choose among two candidates with look-alike philosophies when they go to the polls this fall.

Joseph D. Quinn, a certified public accountant from Denton, is the only announced Democratic challenger to incumbent Republican Rep. Robert Bauman. Quinn believes the way he can win election in this extremely conservative area is by showing that his views are as far to the right of the political spectrum as Bauman's.

"Is that possible?" laughed Bauman, when told of Quinn's plan yesterday. Bauman was host to about 400 supporters at a picnic in the yard of his waterfront home here.

Some of Bauman's supporters already are looking beyond this fall to a time when they see the 41-year-old three-term representative as a conservative candidate for president, a sort of latter-day Barry Goldwater or Ronald Reagan.

This view of Bauman's future prospects, however, has not daunted Quinn, 38, who announced his candidacy a month ago "without conferring with a soul" after it appeared that no Democrat was going to oppose Bauman.

Quinn said he does not disagree much with Bauman's philosophy but is concerned that as the self-styled conservative watchdog of the House of Representatives, Bauman has neglected the folks here on the Eastern Shore, and his other constituents in Harford County and the three counties in southern Maryland that make up the first district.

Quinn contends that Bauman spends so much time on the floor of the House - Bauman has a 99 percent voting record and is nearly always present when the House is in session - that he neglects constituent work. The Democratic challenger also argues that as a member of a majority party, he would be more effective in getting legislation passed.

Quinn, who is the secretary of Maryland's Democratic State Central Committee, hopes a populist campaign will allow him to capitalize on the 2 1/2-to-1 Democratic registration edge in the district.

At his picnic yesterday, Bauman was the picture of the good guy, greeting guests in an all-white ensemble that included an embroidered shirt that he purchased in Panama during a trip there earlier this year. He had taken that trip to gather information in an unsuccessful attempt to influence the outcome of the Senate debate on the two Panama Canal treaties.

One of the guests at the picnic, retired Army Col. Noah Ames Pennewell of Snow Hill, said, "Here is the number one congressman in the U.S.A. and presidential timber" as he shook Bauman's hand.

Norman I. Shapira, who is Bauman's campaign manager in Calvert County in southern Maryland, and who is also a retired Army colonel, added that, while "we will campaign against Quinn as if he were the strongest possible challenger, we're also looking ahead two and four and six years to when Bob may be running for the Senate or the presidency."

Quinn was campaigning yesterday in Charles County. Although he has no experience in public office, Quinn has faced crowds before. In 1958, 1959 and 1960 he was minor league baseball player with the old Washington Senators-Minnesota Twins farm system. Asked what position he played, Quinn said, "Batter. I hit more homers in the rookie (league) than Boog Powell, but I wasn't very good at catching the ball."

When asked about Quinn's contention that he could better serve the constituency of the first district, Bauman said that, because he commutes from his 140-year-old farmhouse daily, he sees the voters at the gas station, grocery store and schoolhouse when he drops off his children en route to Washington.