Rep. Edward Markey

n 2002, Congress passed legislation requiring the federal government to make potassium iodide tablets available to communities located within 20 miles of a nuclear power plant. Edward Markey, who authored that amendment to a larger bioterrorism bill, argued that potassium iodide is needed to protect the public from a potential terrorist attack on one of the nation's 103 commercial nuclear power plants. Potassium iodide can prevent thyroid cancer in people exposed to radiation.

In the aftermath of 9/11, Markey has emerged as a tenacious watchdog, relentlessly prodding the Bush administration to crack down on what he sees as critical gaps in the nation's security. "I've come to the conclusion that the administration doesn't want to spend enough public money to deal with the issue" of homeland security, Markey charged in an interview. "But simultaneously, they also don't want to impose requirements that would require the private sector to spend the money to provide security. So there is a huge regulatory black hole, a whole set of openings that remain to be exploited by Al Qaeda."

Markey, 57, a senior Democrat on the Energy and Commerce Committee, said he will continue to push for legislation forcing the Nuclear Regulatory Commission to require tougher security testing at nuclear power plants. And he's an outspoken advocate of requiring all cargo shipped aboard passenger and air transport planes to undergo stricter inspection. In 2003, Markey successfully won House approval of amendments that would have imposed tough new security measures on nuclear plants and air-cargo shippers. But Senate Republicans subsequently blocked his provisions during conference committee deliberations over larger bills.

Markey's campaigns are opposed by business lobbyists but applauded by public-interest groups. "I can't think of another congressman that has been as forward-looking on the air-cargo issue," said John Safley, president of the Coalition of Airline Pilots Associations.