Roman Catholics in the US have delivered a petition asking Cardinal Roger Mahony to stay away from the conclave in Rome to choose a new pope.
The former Archbishop of Los Angeles was stripped of his duties last month over allegations he protected priests accused of child sex abuse.
Continuing scandals over sex abuse in the Church have cast a shadow over the process of choosing a new pope.
Benedict XVI – who is abdicating – is giving his final Sunday blessing.
Pope Benedict, 85, is due to step down on Thursday. Tens of thousands of people have gathered at St Peter’s Square to hear the Angelus blessing.
‘Slap in face’
Activist group Catholics United gathered nearly 10,000 signatures asking Cardinal Mahoney to recuse himself from the conclave that will chose the next leader of the world’s Catholics.
Handing in the petition in Los Angeles, the group’s communications director, Chris Pumelly, said he was delivering a “message of pain” from thousands of Catholics.
“Cardinals, bishops and leaders of the church, listen to the cries of your flock, respect the victims of abuse and cover up, don’t run from it,” he said.
“Your scandal brings pain to the faithful.”
Benedict XVI is the first Pope to resign in six centuries
On Saturday Cardinal Mahony answered questions for more than three hours from lawyers investigating sexual abuse by priests while he was Archbishop of Los Angeles from 1985-2011.
Church files unsealed under a court order last month show that in the 1980s he sent priests known to be abusers out of California to protect them from criminal prosecution.
The Cardinal was expected to board a plane for Rome shortly being questioned under oath.
On Friday he tweeted that were just hours to go before his departure.
But Joelle Casteix of the activist group Survivors Network of those Abused by Priests said he should not be involved in the conclave.
“It’s a total slap in the face to victims to think he can cover up 25 years of child sex abuse and then go prancing off to Rome like a prince of the church,” she said.
Roger Mahony is one of 177 cardinals under the age of 80 called to the Vatican to vote for the next pope following Benedict XVI’s surprise announcement last week that he was abdicating because of ill-health.
Sex abuse by priests around the world was one of the defining issues of Benedict’s eight-year reign.
The whiff of scandal involving Cardinal Mahony and a separate case involving Scottish Cardinal Keith O’Brien is overshadowing the transition period to the next papacy, the BBC’s David Willey in Rome says.
On Saturday the Vatican criticised the media for reporting “misinformation” about alleged intrigue and corruption in the church.