Parties loyal to President Alvaro Uribe appeared headed toward resounding victory Sunday in congressional elections seen as a test of the U.S. ally's popularity ahead of his race for a second term.

Leftist rebels, in an attempt to embarrass Uribe, had tried to disrupt voting and were blamed for the death of more than two dozen people in attacks across the nation's rural countryside in recent weeks.

But with 200,000 soldiers deployed at polling stations across the Andean nation, the voting was the safest in two decades, the interior minister said.

The violence reported was the burning of three buses in the capital and a car bombing in the northwest province of Choco. No one was injured in the attacks.

With 67 percent of the vote counted, supporters of Uribe's all-out war on leftist guerrillas looked poised to take 70 of 102 seats up for grabs in Colombia's senate. Voting also took place to elect 166 representatives for the legislature's lower house.

Uribe is up for re-election on May 28, having amended the constitution so he could seek a second consecutive term, which if successful would make him the first president to do so in more than a century.

According to recent polls, Uribe is on track to easily cross a 50-percent threshold to win a second term and avoid a runoff with the next closest vote getter.

His closest rival was expected to be Horacio Serpa, leader of the opposition Liberal Party, who finished second to Uribe in the 2002 presidential race.

Praising the relative calm, Uribe called on Colombia's main guerilla group, the Revolutionary Armed Forces of Colombia, known as the FARC, to abandon its insurgency.

``I call on the FARC to recognize Colombia's tireless commitment to democracy and take serious steps to achieve peace,'' the president said in a brief radio address.

Strong backing in the legislature should bolster Uribe's efforts to push through ratification of a free trade agreement with the United States and maintain momentum for his military crusade against the FARC.

The rebel group, meanwhile, said the reported mass desertion of 70 rebels was a government invention intended to bolster the fortunes of Uribe's allies ahead of Sunday's elections.

According to rebels, known as the FARC, the column that supposedly deserted never existed and the man who claimed to be its leader was never a FARC fighter.

On Tuesday, the government touted the bloc's demobilization as the largest desertion from the FARC since Uribe took office in 2002 - proof of the success of his military offensive against the FARC.

With ballots still being counted in 32 provinces, where 166 seats in Colombia's House of Representatives were up for grabs, it was not immediately clear how much influence recently demobilized paramilitary groups would wield.

The United States and United Nations say paramilitary leaders are trying to convert battlefield gains into political capital by bribing politicians and using threats of violence to intimidate voters.

Paramilitary leaders have been trying to win support for legislation that would prohibit their extradition to the United States, where many are wanted on charges of drug trafficking.