Taking a hard-line stand against proposed light rail projects in Baltimore and the Washington suburbs, former Gov. Robert L. Ehrlich Jr. might have driven a wedge between himself and business leaders in regions where he needs to collect votes.

At a recent round table in Montgomery County, Ehrlich said he would scuttle Democratic Gov. Martin O'Malley's plans for light rail on Baltimore's Red Line and Washington's suburban Purple Line - possibly but not necessarily replacing them with dedicated bus lanes.

The Republican's move could endear him to transit skeptics and core constituencies in rural and outer suburban Maryland who use roads heavily and who give little thought to bus and rail systems.

But he runs the risk of alienating traditionally Republican-friendly business leaders who favor both projects, largely because they believe light rail would spur development and job growth along the lines.

In particular, Ehrlich's opposition to the Purple Line plan has put him at odds with Washington-area business groups who were among his staunchest allies in the fight to build the Intercounty Connector, a cause that helped propel him to victory in 2002.

After Ehrlich's remarks, the head of the Greater Washington Board of Trade said he was "scratching my head" over whether the former governor had come to Montgomery to win votes or lose them.

Jim Dinegar, president of the business group, said his organization stands "foursquare" behind O'Malley's choice of light rail as the "locally preferred option" on the Purple Line. He said Ehrlich's rejection of light rail in favor of a bus project is "going to raise a lot of eyebrows in Montgomery County."

"The passion around the Purple Line is very strong and absolutely will have implications for voters," Dinegar said.

Donald C. Fry, president of the Greater Baltimore Committee, said his organization strongly backs light rail on the Red Line to get workers to jobs.

"We are adamant that the benefit of the Red Line is a central issue for the business community," he said.

Ehrlich's preferred alternative, known as bus rapid transit, involves setting aside bus-only lanes along at least part of a transit route. The concept is strongly supported by academics at conservative think tanks but has drawn little backing in public hearings on the two transit lines.

While transportation matters are expected to play a secondary role in an election year in which jobs and the economy are driving the debate, some voters could be swayed by the issue.

Todd Eberly, a professor of political science at St. Mary's College in Southern Maryland, said Ehrlich's position gives O'Malley an opening in the swing counties where the race could be decided.

"For so many of the voters in the counties Ehrlich needs, they want the expanded mass transit," Eberly said.

Voters in Anne Arundel, Charles, Frederick and Howard counties would take a decision to cut rail projects in Montgomery and Prince George's as a sign that they could never expect such service to come their way, he said.

Ehrlich is pinning much of his hope for victory in heavily Democratic Maryland on improvement in his 2006 totals in Montgomery, the state's most populous county.

Ehrlich spokesman Andy Barth said the former governor rejects the light rail approach because "the dollars do not exist" to build the systems without a big tax increase. He said O'Malley was not being candid about the state's finances.

"We do not favor going forward with that now because it's not cost-effective," Barth said. "It's not something we can afford. We don't want to spend money we don't have."

Rick Abbruzzese, a spokesman for O'Malley, said the decision in favor of light rail was made only after extensive consultation and study.

"With respect to both projects, they have been debated for years and it's time to move forward," Abbruzzese said.

Maryland is seeking federal approval for funding for the two light rail projects, which would pay roughly half of the cost. The state would have to raise the other half of the money when its Transportation Trust Fund could still be recovering from a recession-driven revenue slump that has forced more than $2.5 billion in cutbacks in recent years.

The estimated cost of the Red Line light rail plan chosen by O'Malley last year is $1.8 billion. It would run from Woodlawn in the west to Bayview in the east, with tunnels carrying it under downtown and Fells Point as well as Cooks Lane in West Baltimore. The plan has the support of Baltimore city and county governments.

The Purple Line would run from Cheverly in Prince George's County to Bethesda in Montgomery, creating an east-west corridor that would ease travel between the two counties without requiring a subway connection in downtown Washington. The cost of the project, supported by most elected officials in Montgomery and Prince George's, is estimated at $1.6 billion.

According to Ehrlich, that's too much.

The planning processes for the Red and Purple lines got their start when Ehrlich was governor. As part of that study, Maryland Transit Administration officials came up with cost estimates for light rail and bus rapid transit.

That exercise found that while light rail is more expensive to build, it attracts more riders and in some cases saves on operating costs.

A bus rapid transit system is not cheap to build. The Red Line bus plan most comparable to the light rail plan selected by O'Malley was projected to cost about $1.2 billion. The annual operating costs for buses was estimated at $5.9 million compared with $3.2 million for light rail. Operating costs are generally paid locally, without a federal match.

Barth said that while Ehrlich prefers bus rapid transit to light rail, he is not promising to build either one. He said the option of not building either system remains in play.

Ehrlich's cautious stance toward big transit projects could increase enthusiasm for his candidacy in rural areas where he is already popular. State Sen. E.J. Pipkin, a Republican who represents the upper Eastern Shore, said O'Malley has been emphasizing mass transit in urban areas at the expense of the rest of the state.

"We've got two states," Pipkin said, referring to the broad divide between different parts of Maryland. "You've got one state that's pushing for all mass transit and another state that doesn't get [money] to maintain the roads we have."

Wendell Cox, a visiting fellow with the conservative-leaning Maryland Public Policy Institute, contends that light rail is far less effective than bus rapid transit.

"The problem with light rail is that it is so costly with so little benefit," he said. "It's really the difference between building a transit system and building a monument."

But Dinegar said bus rapid transit has been studied thoroughly in Washington and "doesn't get it done."

"A light rail system signals permanency to transit-oriented developers," said the president of the Greater Washington Board of Trade. "A bus rapid transit system signals nothing but uncertainty to developers."

Eberly said that while Ehrlich's opposition to light rail seems to play into his theme of fiscal responsibility, the Republican had erred in the issue he chose to highlight it because business wants infrastructure investment.

"It can really counter Ehrlich's business-friendly message," the political science professor said.

In addition to votes, Ehrlich's stand could cost him in terms of fundraising from businesses that might like his stance on taxes and regulation but oppose him on transportation issues. But he also could achieve gains by cutting into O'Malley support in heavily Democratic areas that oppose the governor's light rail plans.

Ben Rosenberg, a leading opponent in Canton of the current Red Line plan, said there's no way a bus system could be worse for the Baltimore neighborhood than surface light rail on Boston Street.

"Anything that doesn't require the construction of a double-track railroad has got to be better," he said.

michael.dresser@baltsun.com