Amid a wave of violence, Colombians will vote Sunday for new legislators in elections that could shed light on presidential races later this year.

All 100 senators and 163 members of the House of Representatives will be chosen. Election-watchers will look to the voting to gauge the strength of Colombia's two major political parties, the Liberals and the Conservatives, in anticipation of presidential elections on May 8.

Leftist guerrillas, in an effort to disrupt the elections and seize territory, have stepped up attacks recently and have threatened American targets.