Maryland's Democratic Party has canceled plans to hold a presidential straw poll at the conclusion of its annual party conference Sept. 24 after supporters of former vice president Walter F. Mondale reacted angrily to the idea.

According to sources in the state party, there had been considerable pressure from Mondale's people to call off the poll from the outset. Democrats sent out a letter June 3 announcing the cancellation, prior to last weekend's Wisconsin straw poll, which resulted in an embarrassing loss for Mondale to Sen. Alan Cranston (D-Calif.).

Mondale swept through Maryland in March, picking up the endorsements of most of the state's major officeholders and holding a successful fund-raiser in Baltimore County, all on the same day. Since then, however, the feeling among state politicians is that Sens. John Glenn (D-Ohio) and Gary Hart (D-Colo.) have been making inroads and could benefit from a straw poll.

Yesterday, the Mondale campaign denied putting any pressure on Maryland to cancel the straw poll. "We'd be more than happy to be involved in that sort of the thing if the Maryland people wanted to hold it," said campaign manager Bob Beckel. "We have no interest and no reason to try to affect what a state does with its convention and we certainly did not try to impact on the decision made in Maryland."

In Maryland, Mondale supporters insisted their opposition had to do with procedure. "We were against it because the decision to hold it was made without consulting us," said Peter Marudes, chief aide to Sen. Paul S. Sarbanes (D-Md.) and Mondale's campaign chairman in the state. "They sent out letters inviting the presidential candidates to attend and informing them there would be a straw poll, but they never even asked us about it."

The letter announcing the straw poll was sent out in May by Lanny Davis, a member of the Democratic National Committee and one of the chief organizers of the party conference. Davis is not committed to any of the candidates.

"We had thought of having a straw ballot prior to the 1980 election but the Carter-Kennedy thing had so much potential for bad blood that we called it off," Davis said yesterday. "But this year, with no incumbent Democrat, we thought a straw poll might be a good idea.

"After we sent out the letters announcing it, though, we started getting questions about logistics, who could vote, who couldn't, how would eligibility be determined, things like that. What's more, when I saw what was happening in places like Massachusetts and California, I realized that the straw polls were subverting the whole system. We decided we didn't want to make the same mistake those other states had made, so we called it off."

Others involved in the decision said that logistical problems were a factor, but the pressure from the Mondale people was, "considerable."

"They were afraid it could embarrass them," said one source. "Mondale's got most of the major people in the state on his side and a straw poll just meant spending lots of money and time and perhaps getting embarrassed."

Mondale's Maryland supporters include Sarbanes, Gov. Harry Hughes, Attorney General Stephen H. Sachs, Rep. Michael Barnes.

Hart spokeswoman Kathy Bushkin did not sound disappointed yesterday that there would be no poll in Maryland. "Our approach to straw polls is that they provide a chance for the candidates to make their views known," she said. "If Maryland is still inviting the candidates to speak, that is fine with us."

Glenn's campaign office said it had not received notification that the straw poll had been canceled.