Washington ? Agencies across the federal government are launching an aggressive and unusually open offensive aimed at thwarting terrorist plots before and during the presidential election in November.

Numerous law enforcement and counterterrorism officials also warned last week that a heightened threat of terrorist attack will persist through the January inauguration.

The government’s strategy will include heavy surveillance by the FBI, increased checks of terrorism watch lists by local police and heightened security at polling places on Nov. 2, officials said.

Counterterrorism officials concede they do not have new or specific intelligence outlining plans for an attack, but say they remain alarmed by indications that al-Qaida and other terror groups might seek to influence U.S. elections as they did last spring in Spain by setting off bombs on Madrid commuter trains.

By publicizing the government’s efforts, which will begin in earnest later this week, authorities say they hope to forestall any plans for similar attacks here.

The FBI, which is sharply limiting personal leave and transferring hundreds of agents to the effort, will focus heavily on individuals within the United States who are suspected of having ties to al-Qaida and other terrorist groups or who sympathize with their causes, according to officials who have been briefed on the plans.

Officials said the FBI’s tactics, which will be outlined in an electronic communication to field offices, would include aggressive and often overt surveillance, widespread interviews and, in some cases, arrests. Local police will be urged to run the names of suspicious people through the federal government’s terrorism watch list, even during traffic stops and other minor encounters.

A national election security planning bulletin will be sent Tuesday to the 50 states and the District of Columbia, containing guidelines for coordination of law enforcement, polling place and ballot-counting security, legal powers to order emergency election changes and public communication from now through Election Day.

Authorities are focused on a series of dates, starting with the annual meetings that begin Friday at the International Monetary Fund and the World Bank, both of which remain under a heightened “orange alert” with other potential financial targets in Washington, New York and New Jersey.