The cycling champ and cancer survivor joined Los Angeles Mayor Antonio Villaraigosa on Monday to urge support for the California Cancer Research Act, which would increase taxes on cigarettes by $1 a pack to raise more than $500 million a year.
Voters could decide the tax as soon as June if Gov. Jerry Brown is granted a special election by legislators, a decision expected by March 11.
Otherwise, the initiative would land on the February 2012 ballot.
The act is backed the American Cancer Society, American Lung Association, American Heart Association and other advocacy groups.
Armstrong, who recently retired, is a seven-time Tour de France winner.