But she could not do it, Chamberlin said in the letter, she later posted on Facebook. "I could never look myself in the mirror again with self-respect."
The choir's participation in the inauguration would "severely damage" its "image and networking," she said, adding that many "good people throughout this land and throughout the world already do and will continue to feel betrayed. ... I know that I too feel betrayed."
For the singer, it is a moral issue, she wrote. "I only know I could never 'throw roses to Hitler.' And I certainly could never sing for him."
Chamberlin, who said she has been with the choir for five years, did not respond to interview requests and The Church of Jesus Christ of Latter-day Saints declined to comment on her status in the famed group or on how many others might have dropped out or complained.
"Participation in the choir, including the performance at the Inauguration, is voluntary," church spokesman Eric Hawkins reiterated in a statement Thursday. "Only a limited number of choir members are participating (the number is limited by the inaugural committee), and none are required to participate."
LDS leaders announced the decision to perform last week. Not all 360 singers will make the trip, but church officials have said about 215 are expected to volunteer.
The choir previously sang at swearing-in ceremonies for George H. W. Bush (1989), Richard Nixon (1969) and Lyndon Johnson (1965). It performed in inaugural parades for George W. Bush (2001), George H. W. Bush (1989) and Ronald Reagan (1981).
Soon after the announcement about the choir's appearance at Trump's Jan. 20 event, Randall Thacker, a lifetime Mormon and past president of Affirmation, a support organization for gay Latter-day Saints, launched a petition, arguing the choir's participation "does not reflect the values of Mormonism and does not represent its diverse 15-plus million members worldwide."
By Thursday, it had nearly 19,000 signatures, most of whom reportedly are Mormons from across the U.S. and around the globe. Many expressed being "saddened and perplexed" by the decision to send the choir and urged LDS leaders to reconsider.
Meanwhile, choir members who have concerns about Trump or their participation could opt not to put their names into the lottery used to select those to perform.
Response to the choir's appearance "has been mixed, with people expressing both opposition and support," Hawkins said last week in a prepared statement.
The choir's long tradition of performing for presidents "is not an implied support of party affiliations or politics," he said. "It is a demonstration of our support for freedom, civility and the peaceful transition of power."