Voters in California yesterday weighed in on a ballot measure that would increase the state tobacco tax by $1 a pack to raise an estimated $441 million a year for research on cancer and other tobacco-related illnesses. At the polls yesterday, 49.2% of voters supported Proposition 29, and 50.8% voted against it. That represents a gap of about 63,000 votes. But supporters aren't giving up yet, arguing that some 200,000 to 500,000 mail-in and drop-off ballots have yet to be counted. "We're not conceding," says campaign spokesman Ricardo Quinto.