After a campaign marred by accusations of vote-buying, President Ernesto Samper's scandal-plagued party lost ground in legislative elections as many disgusted voters chose anti-corruption candidates.

Samper's Liberal Party nevertheless remains the most powerful force in Congress, widely considered Colombia's most corrupt institution."This was a vote of protest against corruption and cronyism," said an elated Antonio Navarro Wolff, an ex-guerrilla who won a seat Sunday in the 161-member House of Representatives.

Navarro, an independent, ran on his laurels - a record of "zero corruption" as mayor of the southern city of Pasto, for which business leaders named him 1997 mayor of the year.

The Liberals lost eight seats in the 102-member Senate, dropping to 48 with 94 percent of the vote counted. The main opposition Conservatives fell from 20 to 14 seats, with 22 other parties and movements winning the remainder.

In the House, the Liberals dropped by eight seats to 80. The Conservatives fell 10 seats to 30.

The Liberals and their allies had controlled nearly 60 percent of both chambers.

Navarro said no more than 10 percent of candidates in Sunday's elections were from outside Colombia's traditionally corrupt political class.

Among the outsiders was Ingrid Betancourt, a Liberal dissident catapulted to national prominence when she called Samper "a criminal" in 1996 Congressional debate over his alleged links to drug traffickers.

But many lawmakers closely associated with drug corruption won election.

Leftist rebels kidnapped mayors and election officials and burned ballots to try to impede the vote. Their attacks, threats and transport bans led to canceled balloting in at least 46 of Colombia's 1,072 municipalities.