WASHINGTON — The 177 Republicans in the House of Representatives plan to unanimously oppose health-care legislation that would constitute the biggest expansion of insurance to Americans in decades, illustrating the huge divide that remains between the two parties on key issues and setting up a major debate in next year's elections.

The universal opposition to the health-care bill, which Congress could vote on as soon as Saturday, was long expected, but Republican wins in the Virginia and New Jersey gubernatorial races on Tuesday further emboldened the GOP in its stance. If all Republicans vote no on the health reform bill, it would mean not a single Republican up for election next year in the House or the Senate has backed the two biggest initiatives of President Barack Obama's first year in office — the $787 billion economic stimulus plan and the health-care legislation.

Top officials in both parties said the unified GOP opposition would help their side. Republicans said they were trying to block a bill that has generated strong opposition around the country, while Democrats said the health-care vote would cement the view that Republicans aren't acting to help Americans suffering through the recession.

Rep. Chris Van Hollen, D-Md., head of the Democratic Congressional Campaign Committee, said voters next year will ask Americans "who was on our side" as the economy declined.

"When they ask themselves that question, they'll see, unfortunately, that our Republican colleagues were AWOL," he said."

Rep. Eric Cantor of Virginia, the No. 2 Republican in the House, said, "The elections that took place in New Jersey and Virginia show the public is looking for a better way."

Republicans have listed a number of policy objections to the bill, including its overall cost of more than $1 trillion and the creation of a government-run insurance option as an alternative to private insurance companies. Most in the GOP caucus feel the latter is an excessive intervention of the government into health care.

Some Republicans who live in more liberal areas, such as Rep. Michael N. Castle, R-Del., said they would consider voting for the final health-care bill that emerges after the House and Senate negotiate their competing versions of the legislation. The Senate bill, while not completed, will not likely include a 5.4 percent tax on couples who earn more than $1 million that is in the House version, which Republicans oppose.