Bennett’s lawyer Beatrice Mtetwa told reporters the defense team had asked Judge Chinembiri Bhunu during a hearing in his chambers "whether he could hand over to another judge".
Bhunu said he would give his answer Monday, she said.
The trial had been due to begin hearing evidence on Thursday, after Bhunu on Wednesday dismissed applications from both the prosecution and the defense relating to the credibility of the evidence.
Bennett’s lawyers say the state’s case is based on an unsigned confession from a convicted arms dealer, Peter Hitschmann that was obtained by torture.
The defense had wanted Hitschmann excluded from testifying. The state had sought to bar the defense from arguing Hitschmann was tortured into making the confession.
Mtetwa said she feared that if Bhunu continued to preside over the trial, "it might be prejudicial to Mr Bennett".
Bennett, 52, a white farmer whose lands were seized by Mugabe allies, is charged with the possession of weapons for the purposes of banditry, terrorism and insurgency in 2006. If convicted, he could face the death penalty.
Critics of President Robert Mugabe are regularly accused of plotting to overthrow him.
The MDC says the case is a ploy to keep Bennett out of the country’s nine-month-old unity government. Prime Minister Morgan Tsvangirai has nominated Bennett for the post of deputy agriculture minister.