The toughest security test for the Democratic National Convention (search) could come if John Kerry decides to take a stroll -- from his Beacon Hill home to the convention site.

Organizers are taking unprecedented security steps at the first national political convention since the Sept. 11 terrorist attacks -- closing nearly 40 miles of major roads, banning parking around the FleetCenter and providing training to Boston police from experts who have responded to suicide terrorism in Israel and large crowds in Northern Ireland.

The decisions were made before federal law enforcement authorities warned on Wednesday that terrorists might target high-profile events this summer, including the political conventions (search). The Democratic gathering is July 26-29.

But for all the planning, the one wild card for organizers is if Kerry decides to make the mile-long walk from his townhouse in the exclusive Beacon Hill neighborhood to the FleetCenter in the city's working-class North End.

"Obviously, we will be prepared if he does decide to do that, and we will provide a safe and secure environment for him to do that in," said Secret Service spokeswoman Ann Roman.

Such a walk could provide drama for the presidential candidate.

In 1992, when the Democratic roll call clinched his nomination, Bill Clinton, his wife Hillary Rodham Clinton and daughter Chelsea crossed the street from a celebration at Macy's to thank the delegates at Madison Square Garden (search) in New York. The trio joined hands and walked through a section of the store and across the street for a brief visit to the convention hall.

A possible Kerry walk would pose a greater challenge as crowds would likely gather along the route to catch a glimpse or shake his hand.

Brian Jenkins, a terrorism and security specialist at the Rand Corp., said that whenever a president or presidential candidate plunges into a crowd, it is a major concern. He said the Secret Service and police would likely provide an outer ring of security along the route and then an immediate ring around Kerry, as well as police on rooftops, at intersections and numerous locations along the route.

"It's a security challenge, but it regularly happens," Jenkins said. "It's a significant challenge, especially in this age."

Kerry aides have not said whether the candidate plans any walk from his home to the convention.