The Small Business Administration this week revamped a controversial plan  aimed at boosting the number of federal contracts awarded to women-owned firms by making more businesses eligible for preferential treatment in the procurement process.

The revised plan would allow more set-aside contracts for women businesses owners in 31 industry groups, up from just four under the original plan proposed in December. The government already has a mandated target of awarding five percent of federal contracts every year to women-owned businesses. Currently, these businesses receive only about 3.5 percent.   

In the past year, women's business groups and lawmakers  have called on the SBA to either expand the plan or scrap it.

According to the agency, the limited number of eligible businesses under the initial plan was based on a RAND Institute study identifying industries that were underrepresented by women-owned firms in the federal procurement process. In a statement issued this week, the SBA said the study was flawed as a result of reporting problems in the government contractor registry, which currently lists more than 100 industry categories.

Despite the changes, opponents say the plan continues to undermine access to federal contracts for women-owned firms.

"Interpreting just 31 out of more than 100 industries as underrepresented is insulting and hardly an improvement from the SBA's earlier ruling," Sen. John Kerry (D-Mass.), the chairman of the Senate Committee on Small Business and Entrepreneurship, said in a statement.

He said the new plan creates "more roadblocks and does nothing to make it easier for women to compete."

The new plan is now open for public comment.