A high school teacher and a Holocaust scholar was placed on paid leave after drawing parallels between President-elect Donald Trump and Adolf Hitler in his class.

Frank Navarro, who teaches at Mountain View High School in California’s Silicon Valley, said he cited some of Trump’s controversial and racially charged statements, such as calling Mexican immigrants “rapists” and criminals and making comments about the Mexican heritage of a judge presiding over a lawsuit against Trump University, to make the case that there are some parallels with Hitler’s persecution of Jews and the Nazi leader’s rise to power.

Both had promised to make their countries “great again,” Navarro said.

He also cited Trump’s previous statements about weakening libels laws to draw comparisons with how the Nazis established control and influence over the independent press.

“It’s an effective way of embedding the lessons that I’m teaching regarding the place of government and the lives of people,” Navarro, who teaches special education, civics and world studies, told The Washington Post. “It’s important to relate history to your lives because, in the end, that’s what it’s going to be about.”

Navarro was placed on paid leave on Thursday after a parent sent an email to school officials complaining about his teaching methods.

Principal Dave Grissom wrote in a letter to parents on Friday that he has an obligation to maintain an “emotionally safe environment” for students while protecting teachers and staff against unsubstantiated allegations, according to the San Francisco Chronicle.

“Regardless of their political affiliation, many of our students show signs of emotional stress,” Grissom said in the letter, the Chronicle reported.

District Superintendent Jeff Harding told the San Jose Mercury News that Navarro could return as early as Monday.

“We are interested in getting Frank back in the classroom . . . We’re just trying to maintain our due diligence,” Harding told the Mercury News. “We have a heightened emotional environment right now with the election. It’s always a challenge to maintain a line in a classroom.”

Navarro, a Mexican American whose father moved to the United States from Guadalajara, has been teaching at Mountain View High School for 40 years. He taught European history and classes focusing on the Holocaust. He became a Mandel fellow for the U.S. Holocaust Memorial Museum in 1997 and studied at the International Center for the Study of Anti-Semitism in Jerusalem, according to the Mercury News.

When confronted about his teaching methods, Navarro said he told the principal that everything he said in class was based on facts.

He said that going by how the complaint was described to him, the parent said Navarro told his students that Trump is Hitler.

“I never said that. That would be historical sloppy thinking,” Navarro said. “What I’ve been teaching is there are remarkable parallels between Hitler and Donald Trump.”

Shortly after he was placed on paid leave, a supporter started an online petition urging school officials to reverse their decision and to “publicly apologize for attempting to intimidate a respected educator.”

The petition had garnered 10,807 signatures as of Sunday afternoon.

Trump’s candidacy has energized white supremacy groups and the alt-right movement, which rejects establishment conservatism and spreads its far-right ideology online.

Anti-Semitic posts also surged on social media during the presidential campaign. According to an October report by the Anti-Defamation League, at least 800 Jewish journalists received anti-Semitic tweets, many from Trump supporters.

A rash of pro-Trump vandalism and Nazi graffiti have been reported in the past few days since the real estate mogul won the election in a stunning upset against Hillary Clinton.

In Philadelphia, for instance, a pair of swastikas were spray-painted on storefront windows, according to an NBC affiliate.

Two similar incidents were reported in New York. One involved a swastika sign and the word “Trump” scrawled on a wall inside a dorm at the State University of New York College at Geneseo. In another incident, the words “Make American White Again” and a swastika sign were spray-painted on a softball dugout in Wellsville.