An American Jewish comedian and outspoken Obama supporter has been attacked by a rabbi for being vulgar and using her Jewish background inappropriately.

Sarah Silverman, who four years ago fronted a campaign called the Great Schlep – a public call to Jewish grandchildren to convince their more conservative grandparents in key swing state Florida to vote for Barack Obama – came under fire in a letter to the Jewish Press.

This year, as America prepares to go to the polls for another presidential election, she has appeared in videos critical of Mitt Romney and the Republicans. At the start of the summer she starred in a video urging a major Republican donor, the Jewish casino magnate Sheldon Adelson, to reconsider his support in return for a lewd proposal on her behalf.

Last month she followed up with one titled "Let My People Vote", highlighting strict and contradictory voter registration polities in certain states. As is her style of comedy, the video featured crude language and sexual references.

Her antics have now prompted an angry letter by Texas youth rabbi Yaacov Rosenblatt, who accused her of having "made a career making public that which is private, making crude that which is intimate".

The Orthodox rabbi, who recently wrote a piece criticising Deborah Feldman, the author of a tell-all memoir about Chasidic life, also suggested that the comedian's openness about sexual matters may be why she had trouble "forging a permanent relationship." He described this as " the most basic desire of the feminine soul" and expressed hope that she would pursue marriage and raise children.

"Your culture may be Jewish, but your mind is not," added Rabbi Rosenblatt, before appealing her to stop using "traditional Jewish terminology" in her political work, "because doing so is a lie".

"Nothing you say or stand for, Sarah, from your sickening sexual proposal to a Republican donor to your equally vulgar tweet to Mitt Romney, has the slightest thing to do with the most basic of tenets which Judaism has taught the world".

The comedian, whose sister is a Reform rabbi, has not yet responded, but her father Donald posted strongly-worded remarks on the website's comments section, in which he noted that while his daughter was listed as one of the world's most influential Jews by the Jerusalem Post, the rabbi was not.