Efforts to reach Mr. Charamut and his campaign on Tuesday were unsuccessful.

Mr. Lesser, a 35-year-old member of the state’s House of Representatives, denounced the mailer as one that plays on age-old, hurtful stereotypes of Jews.

In a statement, Mr. Lesser, who is seeking a Senate seat in central Connecticut, called the tactic “astonishing, even in this environment.”

Last year, the number of reported anti-Semitic incidents in the United States jumped 57 percent, according to an annual report by the Anti-Defamation League.

In the February report, the organization found that such incidents, including harassment, vandalism and physical assaults, climbed to 1,986 in 2017 from 1,267 the year before. The increase coincided with President Trump’s first year in office, and was the largest uptick for a single year since the organization started tracking the data in 1979.

On Sunday, Mr. Lesser, who lives in Middletown, joined a candlelight vigil to show support for victims of the Pittsburgh shooting and to take a stand against hatred and anti-Semitism. His wife, Sarah, grew up four blocks from the Tree of Life synagogue, where the Saturday morning attack occurred.