Colombian organizers of a protest against President Alvaro Uribe's bid for a second term expect about 100,000 marchers in Bogota today as police raise security after foiling a rocket attack on the presidential palace.

Around the country, three labor unions called marches they expect to draw as many as 500,000 people, Carlos Rodriguez, president of the United Workers Federation, said. The unions oppose Uribe's effort to amend the constitution so he can seek another four-year term. The constitutional court is likely to rule this week on the amendment, which congress approved.

``It's not ethical for the president to manage the state's resources at the same time he is a candidate,'' Rodriguez said in a telephone interview from Bogota. ``It's dishonest competition with the other presidential candidates.''

The march comes amid growing concern guerrilla fighters are seeking to undermine Uribe with a renewed offensive in the capital. Uribe, who polls show has a 78 percent approval rating after three years in office, says he is seeking another term to continue his fight against guerrillas and paramilitary factions.

Police last night said they foiled an attack on Uribe, dismantling missile launchers found in a house in the low-income neighborhood of Las Cruces that were aimed at the presidential palace, according to Caracol TV. Two days ago, a car bomb targeting a senator closely allied to Uribe exploded in the business district of Bogota, injuring nine people.

Uribe, who survived at least 18 assassination attempts, has increased the number of troops deployed against guerrillas and drug traffickers, cutting homicides 40 percent and kidnappings by 70 percent. The economy has grown at 4 percent in the last two years on rising consumer and investor confidence. Foreign investment increased 66 percent last year from 2003.

The government forecasts the $117 billion economy will expand another 4 percent this year.

Second Term

Analysts such as Vitali Meschoulam said Colombia could face an experience similar to Argentina and Brazil, where the second terms of former Presidents Carlos Menem and Fernando Henrique Cardoso were ineffective as their administrations became politically diluted.

``It's a concern, second terms never turn out how they are sold. He brings perception of safety, but can he push through what he has promised on the economic front?'' said Meschoulam, a fixed-income strategist with HSBC Securities USA Inc. in New York.

Even now investors like Nicholas Field of WestLB Asset Management say they are concerned Uribe has spent too much time trying to secure his re-election rather than focusing on key policies such as cutting the deficit and reforming social security.

After Uribe

``One four-year term is not enough to create a dictatorship but the process has not been good. He has used up a lot of political capital and taken his eye off the ball,'' said Field, who helps manage $800 million of emerging market debt at WestLB Asset Management in London including about $36 million in Colombia.

Others, like Morgan Harting, an analyst with Fitch Ratings, believe another president would not cause problems for Colombia.

``Uribe's policies would survive regardless of who is in office,'' said Harting. ``Uribe is popular and people have the confidence he can push things on the security front forward but it is wrong to think Colombia can only survive with Uribe in office.''

Today's march will go about 2 kilometers from Plaza de Toros in central Bogota to Plaza Bolivar, where the presidential palace is located.

The unions also are protesting talks between Colombia, Peru, Ecuador and the U.S. aimed at eliminating trade barriers. Rodriguez says a free trade agreement would damage national employment and industry.