A municipal policeman receives a cup before taking part in an drug test in Mexico. (TOMAS BRAVO/REUTERS)

Senators in the evenly divided chamber voted 20-20 on the measure, with Lt. Gov. Bill Bolling (R) casting a tie-breaking vote for passage.

The bill would require that participants in a particular Welfare program, Welfare-to-Work, would be screened to determine if there is reason to believe they are using illegal drugs. If such a determination is made, those participants could be tested for drugs .

Any Welfare-to-Work participant who fails the test or refuses tosubmit to it would be denied benefits under the bill, whose chief patron was Sen. Stephen H. Martin (R-Chesterfield).

A recent Quinnipiac University survey found that Virginia voters strongly support subjecting all welfare recipients to drug tests.

Virginia voters supported the idea of drug testing by a 76 percent to 21 percent margin, in the survey. There is backing from both white and black voters for the policy, with 77 percent of whites and 68 percent of blacks in favor.

Critics of the legislation said that studies have shown that welfare recipients are less likely to use drugs than the general population.

The measure now goes to the House, where its own version of the bill died earlier this session.

This report has been clarified to reflect that under this proposed legislation, drug testing would apply only to participants in the Welfare-to-Work program.