Backers of President Carter's reelection campaign in Maryland have raised $200,000 so far, with 75 percent of the contributions coming from Montgomery County.

The affluent suburb and bedroom community that is home for several White House senior advisers eventually will account for 40 percent of the statewide total once the fundraising is completed, according to state finance chairman Nathan Landow.

Landow, a prominent Montgomery County developer, joined county executive Charles W. Gilchrist and a handful of Democratic politicians yesterday to open the local Carter-Mondale campaign over a cold roast beef buffet luncheon held in Gilchrist's Rockville office.

"The major effort's been in Montgomery," said Landow sporting a well-cut three piece suit. "But Montgomery is where I've found the greatest support [for Carter]."

Four top level Carter aides, including Stuart E. Eizenstat, Jack H. Watson, Stephen Selig and Landon Butler reside in the suburban area known for its well-manicured lawns, exclusive country clubs and swank shopping malls.

The $200,000 already raised -- mostly from Montgomery County dinner parties -- is twice the amount Maryland contributed to Carter's 1976 presidential campaign.

"I've long felt President Carter has been substantially underestimated," said Gilchrist at yesterday's press conference-luncheon. "He's been a superb president. His quality, his character and vision for the country have become more clear in recent months."

Joining Gilchrist and Landow for roast beef and turkey sandwiches were former governor Blair Lee III, United Nations representative Esther Coopersmith, White House special assistant Esther Peterson and Carter's Maryland campaign chariman, Jim Rouse.

Among the tributes to President Carter's record were a few kind words for the Ayatollah Khomeini, a prominent figure in Carter's recent political rebirth.

"Bless his little heart," said Blair Lee of the Iranian religious leader.

"I never stopped supporting Jimmy Carter," the former Maryland governor said. "I was angry at the licking (Cater) was taking at the hands of some of the brittle columnists in the metropolitan newspapers. His record has been a lot better than he ever gets credit for."

Coopersmith was effuseive in her praise for Carter's record of appointing 13 women to ambassadorships.

"It's incredible," she gushed.

Although Blair Lee said he had observed "a waning off" of support for Senator Edward M. Kennedy in Montgomery County, Gilchrist said there was still some Kennedy supporters in the suburban area. The county executive said he thought Carter would prevail.

Campaign chariman Rouse defended the so-called "Rose Garden strategy" in which Carter has stayed cloistered in the White House while emissaries campaigned for him.

"If Carter had gone to Iowa, to debate," Rouse said yesterday, "he would have demolished the people who are scoffing at him. Jimmy Carter is strong enough to appear weak, big enough to humble himself."