As the House inches closer to a vote on House Speaker John Boehner's controversial debt ceiling plan, a group of business associations is urging lawmakers to support the bill or face losing more private sector jobs.

"This legislation is necessary to extend the debt limit and avoid a default on the obligations of the United States," reads the letter sent to members of Congress on the eve of the vote.

The group behind the letter, which includes a wide swath of industry associations and chambers of commerce, warns that default could trigger "immediately higher" interest rates, stock market woes, higher oil prices, and a "loss of economic growth and jobs."

It's the second time this week the powerful U.S. Chamber of Commerce has thrown its weight behind an appeal to pass Boehner's "Budget Control Act of 2011."

"While this legislation is not a solution for all of America's debt and deficit problems, it is a necessary first step in the right direction," wrote R. Bruce Josten, the second-ranking officer at the trade association, in a Tuesday letter to lawmakers.

The endorsement counters arguments against the bill from conservative economic policy think tanks like Americans for Prosperity and the Club for Growth. Americans for Prosperity sent its own letter to Congress calling the bill's "paltry" spending cuts "unacceptable."

Conceding that they "remain extremely concerned" about the federal debt even after penning their support for Boehner's plan, Thursday's group of business associations nevertheless urged Congress not to let the perfect be the enemy of the good.

"While no legislation is perfect, the current proposal cuts spending immediately by more than the extension of the debt ceiling, provides an enforceable mechanism to produce additional spending reductions with extensions of the debt limit predicated on these cuts, and allows for a vote on significant procedural change to our budgeting process," it said.

White House advisers on Tuesday warned that they would counsel the president to veto Boehner's plan if it survives the House and Senate.