Republican Mark D. Fennel, 42, a marketing analyst from Silver Spring, defeated candidate John McKinnis of Calverton in that party’s primary. Fennel had nearly 48 percent with 898 votes, while McKinnis had 41 percent and 771 votes.

The winners will square off in a District 4 special general election May 13.

Praisner said Tuesday night that he would only serve the remainder of his wife’s term and continue her legacy by advocating for controlled development and strict fiscal policies.

‘‘I don’t want that to mean that I’m a caretaker, I look to it myself as being an active council member,” he said. ‘‘I’m not opposed to growth, but we have to have the infrastructure in place before we start talking about growth.”

Praisner said it was premature to talk about his plans until after the general election, but reiterated that he wanting the look for ways to manage growth through mass transportation, with an eye on quality of life in different neighborhoods.

‘‘I want to thank the voters in District 4 for their support of me,” he said. ‘‘I’m very humbled by it.”

Navarro, 42, the school board president and a Silver Spring resident who was born in Venezuela, campaigned as an advocate for minorities and education policies, and had received the backing of many labor organizations. She has said she supports a balanced approach to development that would work with business and labor interests.  

Navarro said Tuesday night she was proud of the campaign she had run.

‘‘This was truly a broad coalition that I think is indicative of the importance of bringing all segments together to work for a balanced future here in Montgomery County,” she said. ‘‘If we’re moving forward, I think it should be about an inclusive coalition.”

Fennel, who was the 2006 Republican nominee for the District 4 seat and is director of the nonprofit group Citizens Against Government Waste, has made property taxes a focus of his campaign, and he has said he will vote against tax increases.

Fennel on Tuesday night was leading the field of Republican candidates including Thomas Hardman, 49, an information technology consultant and Aspen Hill resident, McKinnis, 33, an information technology business owner and Calverton resident, and Robert Patton, 33, an athletic fields specialist and former Peace Corps worker from Silver Spring.

District 4, which includes parts of Burtonsville, Silver Spring, Cloverly, Colesville, Wheaton, Aspen Hill, Olney, Sandy Spring and Ashton, as well as the retirement communities Leisure World and Riderwood Village, is slightly older, less affluent and more diverse than other parts of the county. Community leaders who hosted forums had asked candidates to bring more resources to their east county communities, which some residents say have been overlooked in past years.

The next District 4 representative, however, could play a crucial swing vote on the nine-member council on matters that affect the entire county, such as the pace of development and strategies for combating a $297 million budget deficit.

Praisner voters on Tuesday said they were looking for someone to carry on the legacy of Marilyn Praisner, who died at the age of 66 following heart surgery.

‘‘I liked what his wife was doing in terms of keeping the county in line,” said Calverton resident Laura Day, 59, who voted for Praisner. ‘‘Marilyn served this county very well and I think Don would, too.”

Navarro supporters said they were looking for a candidate with experience who would bring more diversity to the council.

Oitin Martin, 55, said she voted for Navarro because she has a son in high school and education was an important issue for her.

‘‘I looked at the information [Navarro] sent and she has a lot about education and improving the schools,” said Martin, a Silver Spring resident who voted at White Oak Middle School.

With such potentially high stakes, several county officials lined up behind the Democratic frontrunners. County Executive Isiah Leggett (D) and four council members: Phillip M. Andrews (D-Dist. 3) of Gaithersburg, Roger Berliner (D-Dist. 1) of Potomac, Marc Elrich (D-At large) of Takoma Park and Duchy Trachtenberg (D-At large) of North Bethesda, all endorsed Praisner.

Navarro won the backing of Councilwoman Valerie Ervin (D-Dist. 5) of Silver Spring, as well as the reported support of schools Superintendent Jerry D. Weast, who was said to have called union leaders to his North Potomac home Feb. 29 and asked them to back Navarro, according to people who attended the meeting. Elrich and other officials criticized the meeting, about which Weast has declined to comment.

Navarro was also supported by labor unions, minority advocacy groups and the Montgomery County Education Association, while Praisner received an endorsement from the Montgomery County Volunteer Fire and Rescue Association.  

With only two months to campaign before the primary, observers said Praisner’s name recognition and the limited time others had to develop theirs would give him the winning edge.

To compensate, Navarro led a blitzkrieg fundraising campaign in which she raised close to $40,000 that included large contributions from the Montgomery County Career Firefighters, the Mid-Atlantic Regional Council of Carpenters and other labor organizations. It was the money Navarro chose to accept from developers, however, that brought criticism from other candidates.

Praisner, in honor of his wife’s legacy as a slow-growth proponent, had pledged to not accept money from developers, a vow made by several other candidates as well.

Navarro countered by pointing out that Marilyn Praisner also accepted developer money.

Earlier this month, at least two instances of automated campaign phone calls that did not have authority lines warned voters not to vote for Navarro because of her stance toward developers. Those calls, because they had no attribution, violated state and federal law, and were condemned by other candidates.

Praisner was forced to leave the campaign trail for several days after he was hospitalized April 2 and admitted overnight for precautionary tests. The 75-year-old, whose wife died from complications from heart surgery, never revealed his symptoms, but attributed them to stress and said he felt fine after he returned to action a few days later.

The results

Democratic candidates:

Donald Praisner: 3,288

Nancy Navarro: 2,940

Steve Kanstoroom: 804

Patrick Ryan: 402

Republican candidates:

Mark Fennel: 898

John McKinnis: 771

Robert Patton: 114

Thomas Hardman: 96