Parties loyal to Colombian President Alvaro Uribe have won an overwhelming victory in Sunday's legislative vote.
The constitution was changed so Mr Uribe could run for re-election
With 93% of the votes counted, the governing coalition now controls 61 of the 102 seats contested in the Senate.
Results show similar gains in the lower house, with government parties taking 91 of 166 seats voted.
Correspondents say the victory will reinforce Mr Uribe's position as the favourite to win the presidential elections in May.
The Colombian president has changed the constitution so he could stand for a second term. He says he needs four more years in office to implement his tough policies against armed groups and drug-traffickers.
Another result of Sunday's voting was the selection by the main opposition Liberal party of their presidential candidate.
The main challenger to Mr Uribe will be Horacio Serpa, who has already lost two presidential contests.
The BBC's Jeremy McDermott in Bogota says he is not likely to unite the anti-Uribe vote.
The liberals are bitterly divided and the Conservatives have thrown in their lot with the president as their only chance of political survival, our correspondent adds.
On Sunday, the abstention rate among voters reached a record 66%, and 15% of the cast ballots were deemed invalid.
This was blamed on fears of violence that proved largely unfounded, increasing public apathy, and confusion over recent changes in the electoral system.
However, the results have been seen as an endorsement of the president's tough stance in the war against left-wing guerrillas.
Mr Uribe reacted to his coalition's showing by urging the largest rebel group, the Farc, to enter peace talks.
"I call on the Farc to recognise Colombia's tireless commitment to democracy and take serious steps to achieve peace," he said in a brief radio address.
Colombians managed to cast their votes with relative ease after rebel threats of widespread violence did not materialise, the BBC's Jeremy McDermott reports.
Rebels did burn ballot boxes in one area and polling booths in another and in some of the more remote rural regions voters were prevented from getting to polling stations.
But there was not the national disruption of voting that was feared.
Commentators believe that the Farc are keeping their powder dry for the presidential election in May as they have stated their total opposition to the re-election of Mr Uribe, who is backed by Washington.