Mexico's small, left-leaning Social Democratic Party (SDP) calls openly for drug legalization as part of its platform. Now, in the run-up to midterm elections in July, that stance may be attracting attention of the wrong sort. The party reports that at least four of its congressional candidates have been attacked while campaigning, and the party chairman is strongly suggesting that he thinks drug traffickers are behind them.

On Sunday, a PSD campaign worker was injured by flying glass after unknown assailants fired on the vehicle of PSD candidate Emmanuel López in Acapulco. Two days before that, someone threw a Molotov cocktail at PSD hopeful Celina del Carmen Ávalos in Tijuana. Two other party candidates were attacked in separate incidents in Mexico state earlier in the campaign. None were seriously injured.

In a Tuesday press conference, PSD leaders called the attacks "unacceptable" and demanded that the government act to halt them. All four attacks had been reported to local law enforcement, they said.

"He's out of danger," PSD chief José Carlos Díaz Cuervo said of the injured campaign worker. "However, it seems to us unacceptable, requiring of public outcry, that these attacks continue." The attacks signal "a clear intention to intimidate us... something we interpret as a sign we are doing well, disturbing precisely the interests that have this country prostrate before organized crime," the PSD chairman said. "It's time authorities said something about this. These acts of violence cannot be allowed to pass as campaign anecdotes," he said.

When asked directly if he thought drug traffickers were behind the attacks, PSD deputy chairman Luciano Pascoe said the party had no direct evidence to support that theory. "What we are beginning to find is that they (the attacks) are directed against the party, against the proposals, and this speaks of a political profile," Pascoe said. "What they won't achieve with bullets is to silence us."

But Díaz was less hesitant. "Doubtless, unlike the federal government, it appears the drug traffickers do understand that the regulation of that market would take the business away from them and would be a more intelligent way to combat them," he said.

The campaign comes as Mexico's drug war continues to roil the country. Upon taking office in December 2006, conservative President Felipe Calderón began deploying federal troops and police to rein in the so-called cartels, whose battles with authorities and among themselves left 1,500 people dead in 2006. But even as the number of federal troops and police rose to 65,000, with several Mexican border cities under virtual martial law, so has the prohibition-related death toll. It jumped to 2,700 people in 2007 and leapt dramatically to more than 6,000 last year. This year seems to be keeping up with that torrid pace, with some 2,500 people reported killed so far.

The PSD argues that drug legalization would increase public safety by constricting the money supply to the cartels. It also calls for legalization on public health and humanitarian grounds.