BUENOS AIRES — A federal judge asked Argentina’s Senate on Thursday to allow the arrest of Cristina Fernández de Kirchner, the former president, on treason and other charges relating to Iran’s possible involvement in the unsolved 1994 bombing of a Jewish community center in Buenos Aires, which killed 85 people.

The request — made as part of a criminal case — added drama and uncertainty to the legal troubles that have engulfed Mrs. Kirchner, who was in office from 2007 to 2015 and is set to begin a term as a senator on Sunday. She also faces unrelated charges in several corruption investigations.

On Thursday, Mrs. Kirchner called the prosecution politically motivated, and her supporters rallied in Buenos Aires. In a news conference, she said her successor, President Mauricio Macri, was creating a “smoke screen” to divert voters’ attention from controversial pension and labor reforms. “We will not be silent, we will not get scared,” Mrs. Kirchner said.

The judge’s request, which includes an embargo of 50 million pesos ($2.9 million) on the former president’s assets, also deepens the mystery surrounding the 2015 death of a prosecutor, Alberto Nisman, who was investigating the bombing.