Colombia's Uribe signs his own re-election bill

Colombia's President Alvaro Uribe (L) shakes hands with the director of the Colombian Farmers Society, Raul Mejia, during an official ceremony at the presidential palace in Bogota September 7, 2009.

BOGOTA (Reuters) - Colombian President Alvaro Uribe on Tuesday signed a bill calling for a referendum to ask voters if they want to change the constitution to allow the popular U.S. ally to run for a third term next year.

Uribe has not said publicly whether he wants another turn in office. But his government has lobbied hard for the referendum and his signing of the bill indicates he may launch another campaign if given the chance.

The bill, passed by Congress last week, will be reviewed by the Constitutional Court, a process that could take months. The next presidential election is scheduled for May.

Colombia changed its constitution once to allow Uribe to run for a second term in 2006. He is a hero to many for his U.S.-backed crackdown on drug-running Marxist rebels.

But many of his own supporters say a third term would concentrate too much power in the executive branch, upsetting the country's democratic balance of power.

Uribe is Washington's key ally in the Andean region. Socialist leaders in Venezuela, Ecuador and Bolivia have moved to extend their time in power while criticizing U.S. policy and deepening ties with China, Russia and Iran.

(Reporting by Hugh Bronstein; editing by Mohammad Zargham)