In the Southern Maryland swing of his campaign announcement tour this week, Douglas M. Duncan, Democratic candidate for governor, called for the creation of a statewide "research diamond" modeled after North Carolina's Research Triangle and his own county's cultivation of high-tech businesses.

The Montgomery County executive promoted economic development over slot machines as a more sustainable source of revenue to help pay for what he says would be the No. 1 item on his agenda in Annapolis -- public education.

With his pitch to Democratic activists in Calvert County and teachers in Charles County, Duncan sought to underscore his campaign slogan -- "think bigger" -- and to distinguish himself from his Democratic primary opponent, Baltimore Mayor Martin O'Malley, as well as Republican Gov. Robert L. Ehrlich Jr.

"We don't have to settle for slots and squabbling,'' Duncan said Monday during his visit with teachers in the library at J.C. Parks Elementary School in western Charles. "We can have a world-class school system and a world-class economy, if we're willing to think bigger."

O'Malley supports putting a limited number of slot machines at some racetracks to help the state's anemic horseracing industry. Ehrlich has pressed for a more expansive approach to legalizing slots.

On Monday, Duncan's road trip in the 10-year-old recreational vehicle of a longtime political supporter took him across the Patuxent River, past pumpkin patches and tobacco barns. The tour, which began at his childhood home in Rockville last Thursday, is meant to signal that the candidate intends to compete in all 23 counties and Baltimore.

"It's why I'm visiting every county now, why I did it in the summer and why I'm going to do it again. I'm just going to keep coming back," Duncan said before touring Huntingtown High School in Calvert.

Duncan highlighted endorsements he has received from two former Baltimore mayors, Kurt L. Schmoke and State Comptroller William Donald Schaefer.

At the Elks Lodge in Prince Frederick, state Senate President Thomas V. Mike Miller Jr. (D-Calvert) said he expects O'Malley and Duncan to have "crossover appeal" on each other's home turf, but that "both will carry their respective jurisdiction."

That will make other parts of the state, such as vote-rich Prince George's, and even smaller jurisdictions, such as the Southern Maryland counties, more important in the primary.

One challenge in traditionally more conservative Calvert and St. Mary's counties will be overcoming liberal stereotypes of Montgomery County. Many households in Calvert also watch local news coverage from Baltimore, making O'Malley a familiar face.

"This is a very conservative county. When you mention 'MoCo,' there is a group of individuals that make assumptions," said Chris Reynolds, chairman of Calvert's Democratic Central Committee. "They're incorrect."

Reynolds said voters instead need to examine Duncan's record on issues such as his leadership of a diverse population and on the contentious issue of the intercounty connector.

Evan West, an English teacher at McDonough High School, praised Duncan's "think bigger" theme, but he questioned where the money would come from to pay for some of the candidate's proposals, such as boosting retirement benefits for teachers and giving low-income college students tuition breaks.

After hearing Duncan's proposal to encourage technology companies to locate beyond the Interstate 270 corridor and in clusters throughout the state, West seemed satisfied.

"If you're going to grow the budget, you have to grow revenues. That's what they've done in Montgomery County," he said. "That's got to be the model."

Douglas Duncan at Huntingtown High on Monday with his wife, Barbara, and daughter, Conor. He says schools would be his top priority as governor.

Douglas M. Duncan greets junior Colleen Lohmuir while visiting Huntingtown High School's computer lab on Monday.