Editor's note: This story has been updated with comments from Lt. Gov. David Dewhurst.

*Correction appended

Texans applying for unemployment benefits will be subject to a new drug screening procedure in a program scheduled to take effect Feb. 1. But the Texas Workforce Commission said it will not be able to start the program on the state’s timetable because the United States Labor Department has not set the required parameters.

As proponents of the program raise concerns about the Labor Department’s progress, the Workforce Commission is preparing for the testing without knowing who will be tested.

State legislators last year approved Senate Bill 21, which requires first-time applicants in some professions to submit to a drug test if a screening questionnaire indicates possible drug use. Those who tested positive would be ineligible to receive benefits for at least a month, until they passed another drug test. An applicant can enroll in a treatment program to remain eligible for benefits within a week of receiving notice of a failed drug test.

The state was able to put such a policy in place after the passage of a federal law that allows states to drug-test certain people applying for unemployment benefits. But guidelines for such a program cannot be drafted without direction from the Labor Department, which must outline the occupations that fall under the federal law for such drug tests.

In an email last week, Diana Petterson, a Labor Department spokeswoman, pointed to the department’s regulatory agenda, which indicated that proposed rules would be published in March.

She added that there was no timeline yet on the final rules.

Another Labor Department representative said in a July 22 email that the department was working as quickly as it could.

Mississippi passed similar legislation in 2012, and Kansas did so in 2013.

Supporters of the Texas law say it would help ensure that the jobless Texans were truly able to return to work, drug free.

"The passage of Senate Bill 21 was not only great for employers who pay unemployment benefits, but also for the recipients of those benefits who will receive an element of accountability that could help them beat a drug addiction," Lt. Gov. David Dewhurst said in a statement released Monday. He added that the law is "threatened by the kind of foot dragging we've come to expect from Washington."

“I think the delay is unconscionable,” said Bill Hammond, the president of the Texas Association of Business. “The costs will go up. People will stay on unemployment longer, and people will continue to abuse the unemployment system.”

Hammond added that employers, who pay for 100 percent of unemployment benefits, also bear the costs of drug-testing applicants. He said the law would save those employers time and money.

"While I am disappointed, I probably should not be surprised that the feds are taking more time than needed to allow this common sense legislation to take effect," said former state Sen. Tommy Williams, R-The Woodlands, the bill's sponsor.

Without a clear timetable, the Workforce Commission is researching what to include in the screening questionnaire and in the written notice that applicants must receive to navigate the process.

After the Labor Department publishes its final rules and the commission posts its own proposal in The Texas Register, a 30-day public comment period will begin.

The commission presumes that Texans working in the transportation and health care fields, who are among those used to taking drug tests as a condition of employment, will be included in the Labor Department’s list.

“So it’s a limited group of individuals as determined by the DOL occupations guidelines, and from among that group, a limited number would be subject to drug testing,” said Lisa Givens, a Workforce Commission spokeswoman.

*Editor's note: An earlier version of this article incorrectly reported that the proposed rules would be published March 1. It should have been reported that a notice of proposed rulemaking would be published in March.