Bridging party lines, all 16 women in the U.S. Senate on Tuesday unanimously rejected a controversial plan  meant to boost federal contracting for women-owned small businesses, calling it flawed and ineffective.

The proposed plan, unveiled in January by the Small Business Administration  after seven years of review, would allow federal contract officials to give preferential consideration to women-owned businesses in four industry categories identified as underrepresented by women. The agency recently submitted the plan to the Office of Management and Budget for interagency review and clearance.

The move is aimed at achieving a mandated target of awarding five percent of all federal contracting dollars every year to small businesses owned by women. In 2006, women-owned businesses received only about 3.4 percent, according to the most recent government figures.

In a letter to SBA Administrator Sandy Baruah, the bipartisan group of women Senators said the plan was too restricted to fix that shortfall, applying to just four of 140 industry categories in the federal procurement market.

"I find it inexcusable that after wasting well over seven years before issuing any proposal whatsoever, the SBA is now apparently seeking to finalize a defective rule with few, if any, improvements," Sen. Olympia Snowe (R-Maine) said in a statement.

Snowe said women entrepreneurs deserve a contracting rule that helps them receive federal contracts, not a "sham proposal that would provide virtually no benefit."

Sen. Mary Landrieu (D-La.) said the plan falls well short of the goals set out in the Women's Procurement Program, an initiative created by Congress in 2000 and overseen by the SBA.

"After a seven-year delay, the Administration proposed a flawed rule which flies in the face of Congress' intent to give women an equal footing in partnering with the federal government," Landrieu said.