A new coalition of business groups, environmentalists, organized labor and community activists has hired a well-connected lobbyist and is launching an intensive, month-long campaign to persuade Gov. Robert L. Ehrlich Jr. (R) to build the inner Purple Line, a light-rail route that would run between Bethesda and New Carrollton.

The project is envisioned in two phases: a 4.4-mile leg from Bethesda to Silver Spring and a 10-mile leg from Silver Spring to New Carrollton.

The Coalition to Build the Inner Purple Line, which scheduled a news conference for this morning to announce its plans, intends to spend about $20,000 over the next four weeks to win support in Annapolis and Montgomery and Prince George's counties, organizers said.

Its first step was to hire David L. Winstead, Maryland's transportation secretary from 1995 to 1999 and now a lawyer and lobbyist. Winstead, who lives in Montgomery, is a Republican. "He was the logical choice," said Robert Grow of the Washington Board of Trade, a member of the coalition.

The group is pressing its case now because Maryland must decide which transit proposals it will send to Capitol Hill by early March as Congress reauthorizes the nation's transportation spending plan. If a request for funds for the Purple Line is not made by early March, it will be six years before the state gets another opportunity to seek federal money.

"We're going to take the case directly to the governor, to the legislators and directly to the people," said Tom Perez (D-Silver Spring), a recently elected member of the Montgomery County Council and one of the engineers of the coalition. "We have this opportunity now to build. It's the only major transportation project in Montgomery County where we can break ground in 2005 and be moving people by 2008. We've constructed a coalition that I think is unprecedented."

The coalition is made up of some strange bedfellows -- organizations that more often find themselves on opposite sides of an issue. "I don't think the presidents of the Board of Trade and the AFL-CIO have ever spoken together at the same event," said Ben Ross of the Action Committee for Transit, a grass-roots group that has been pushing the inner Purple Line for more than a decade. "This places the issue on a whole new level."

The only leading figure missing from the coalition is Montgomery County Executive Douglas M. Duncan (D). Duncan has objected to the proposed route of the inner Purple Line, which would send trolleys along hiker-biker trails, across the fairways of Columbia Country Club and behind expensive homes in Chevy Chase.

Instead, Duncan favors a heavy-rail line outside the Capital Beltway, bypassing Bethesda and Silver Spring to serve such communities as White Oak, Wheaton and Grosvenor. Under his plan, the stretch between Bethesda and Silver Spring would cost about twice as much as the alignment supported by the coalition -- about $750 million vs. $371 million.

This month, Duncan suggested a new alignment that calls for heavy rail to carry riders from the Medical Center station near the National Institutes of Health, alongside the Beltway and south into the Silver Spring station, avoiding the area around Columbia Country Club.

The new group is focusing on what organizers think could be the compromise that would end opposition to the inner Purple Line: a tunnel that would carry the light rail under the country club and spare it from relocating two golf course holes. State planners estimated several years ago that a tunnel would cost $15 million.

"A tunnel is a political decision," Perez said. "You have to make choices, and you have to make compromises. In an ideal world, I would hope we wouldn't have to [build a tunnel]. In the current political environment in which we find ourselves, it's important to not let perfect be the enemy of good."