Dispirited by a mounting guerrilla threat and allegations of vote-buying, Colombians chose new representatives Sunday to Congress - the institution widely considered their most corrupt.

Leftist rebels, newly invigorated by a huge victory last week, used attacks, threats and transport bans to try to impede the vote.Though 200,000 security troops were mobilized nationwide, Interior Minister Antonio Lopez reported rebel disturbances in 27 mostly remote municipalities that included the burning of ballots and kidnappings of mayors and election officials.

Voting was canceled in at least 10 municipalities, and at least three candidates and 10 mayors were kidnapped as the election approached.

Authorities said five guerrillas and two soldiers were killed in clashes in Risaralda and Santander states, and a car bomb was deactivated outside a police post in Silvania, 12 miles south of Bogota. Fighting was also reported in the same southern jungle zone where the military suffered its worst defeat in 35 years fighting leftist rebels.

President Ernesto Samper, voting in central Bogota, called on Colombia's 20 million registered voters to turn out en masse. In the last congressional election in 1994, turnout was just 30 percent. Polls indicated it would be similar this time.

"We want to tell the violent that we reject their acts of war and that we're going to defeat them once again at the polls," Samper told reporters.

Colombians were choosing 102 senators and 161 representatives to replace the highly partisan Congress that absolved Samper in 1996 of charges he knowingly accepted $6 million from drug lords in winning office four years ago.

The president's detractors say he bought absolution by raiding the treasury and doling out hundreds of millions of dollars among supporters.