MIDTOWN — The Financial District and Long Island City may leap into a fracas about overhauling the Midtown East business district, sources said.

Community Board 1 in Lower Manhattan is expected to vote Wednesday to join boards 4, 5 and 6 on a multi-board task force offering local reaction to Mayor Michael Bloomberg's proposal to rezone a 78-block swath of Midtown to allow newer and far larger skyscrapers.

Board 1's borders end nearly 50 blocks south of the proposed redevelopment zone, but board chairwoman Catherine McVay Hughes insisted that "what happens in Midtown impacts what will happen in downtown."

"There's already an overcrowding of the Lexington Avenue subway line down here, and it's crowded also in Midtown," she said. "So until there's more of an infrastructure in place, it's only going to get more crowded."

Moreover, Midtown and Downtown are also inherently linked in their competition for business tenants seeking so-called Class-A offices, said Wally Rubin, district manager of Community Board 5 in central Midtown, which invited Board 1 to join the task force.

"Board 1 has a big stake in what happens with any new Class-A office space," he said. "Board 1 is concerned about the present and future of Lower Manhattan, so there's a natural interest in what happens — what the plans are for East Midtown — that might draw away business."

Board 1's Planning Committee unanimously voted last week to join the Tri-Board Task Force, which will be redubbed the "Multi-Board" Task Force, Rubin said. The full board, expected to pass the measure, Hughes said, will hold a vote at its monthly meeting Wednesday.

Community Board 2 in Long Island City, meanwhile, has not yet taken any formal action on whether to join the Tri-Board Task Force, Rubin said.

Still, in meetings with task force representatives, Board 2 members expressed interest in joining, sources said.

"Long Island City…has long been thought to be another potential business district. One of the contingents that we have certainly talked about is a need for a citywide strategy for business districts, whether it be East Midtown, Downtown Brooklyn, 125th Street or Long Island City," he said.

Community Board 2 did not return calls for comment.