BOGOTA _ Colombia's former President Alvaro Uribe said he will resign from the Senate after the nation's top court said it was investigating him.
"The Supreme Court has summoned me for questioning," Uribe said in a post on Twitter. "They did not hear me previously. I feel morally impeded to be senator. I will send my letter of resignation so that my defense does not interfere with the duties of the Senate."
The new congress was sworn in last week. Uribe would have been the most influential ally of incoming President Ivan Duque, who takes office Aug. 7.
"This is a seismic shift in Colombian politics," said professor Jorge Restrepo, an economist who heads a think tank that monitors the nation's conflict.
Uribe's exit from congress removes an important source of support for Duque, but at the same the time could boost Duque's ability to act independently of his mentor, Restrepo said.
The court said in a statement that it is investigating Uribe and another senator from his party for alleged manipulation of witnesses.
