The National Association of Home Builders and the National Association of Realtors have joined forces in an advocacy advertising effort designed to prod members of Congress to pass a "housing stimulus plan that will grow our economy, encourage lending, and make mortgages affordable."

Click here to see the ad .

The ads, running this week in The Washington Post, The Hill, Roll Call and Politico, run the headline, "Grow America's Economy. Start With Housing." They then quote well-known economists on the gravity of the housing downturn and state, "CONGRESS: Experts agree. Urgent action is needed to pass housing reforms that will grow our economy and benefit all Americans."

The ad does not present a specific program but says, "Tax credits for home purchases, proper loan limits from the FHA and other agencies, targeted funds for lower rate mortgages are all critical in today's difficult environment."

The NAHB and the Realtors have to date offered separate plans for stimulating the market, and, while they are similar in intent, they differ in size and scope. Each organizaiton is a powerful lobbying force in its own right, but together, they represent the lion's share of the nation's housing industry. The NAHB has 235,000 members; the NAR has 1.25 million.