The campaign fliers, written in Vietnamese, began landing in mailboxes in Little Saigon earlier this month.

One flier showed Democrat Derek Tran, who is running for Congress, smiling in front of the hammer-and-sickle emblem of the Chinese Communist Party. In another, Tran is shown next to Mao Zedong, with a caption that, translated to English, reads: “Don’t let Derek Tran take our country back to socialism.”

The mailers, sent by the congressional campaign of Rep. Michelle Steel (R-Seal Beach), have infuriated some voters in the 45th congressional district. The district is home to Little Saigon, as well as the most people of Vietnamese descent outside of Vietnam.

“Everybody knows campaigns can get really ugly,” said Cynthia Choi, a member of Chinese for Affirmative Action and Stop AAPI Hate. “And what’s been really troubling is the fact that this is an old playbook. Unfortunately, it can be really effective.”

She added: “It is very disappointing that an Asian American candidate is using red-baiting tactics.”

Steel, 69, is in a costly and acrimonious reelection fight against Tran, 44, as the Democratic Party pushes to capture the seat from the Republican Party.

Republicans have a razor-thin majority in the House of Representatives. The race is among a handful across the U.S., including half a dozen in California, that both parties see as pivotal in determining control of the next Congress.

Tran’s campaign has been focusing heavily on Vietnamese American voters, hoping that his story as the son of Vietnamese refugees will help flip the district from red to blue.

Steel, too, is pushing to bolster support among Vietnamese voters, particularly those who fled Vietnam after the fall of Saigon in 1975 and who have been loyal for decades to the Republican Party.

The Steel fliers describe Tran having support from “socialists like Bernie Sanders.” (Tran said Sanders hasn’t endorsed him.)

Two of the fliers include a translated quote from a story about the congressional race written by the co-chair of the Southern California Communist Party in People’s World, the Marxist-Leninist publication.

The quote reads: “Tran is a first-time candidate, but he exceeded all expectations by winning the primary against his opponent, who had the full support of the Democratic Party establishment.” In the March primary, Tran defeated Garden Grove City Councilmember Kim Nguyen-Penaloza by 367 votes, finishing second behind Steel.

Another mailer highlights Tran’s supposed ties to China, saying he owns “thousands of dollars of cryptocurrency linked to China,” and that he has an account on TikTok, the social media platform owned by the Chinese company ByteDance.

Tran said in an August financial disclosure that he holds between $33,005 and $145,000 in Bitcoin, Ethereium, and another cryptocurrency through the exchange platform Binance. (China banned cryptocurrency trading in 2021.)

“It’s such dirty, dirty tricks,” Tran said. “This is a desperate attempt by a losing campaign. She’s throwing everything at the wall, including the kitchen sink, to see what’s going to stick.”

The Steel campaign said their mailers followed months of attack ads, tweets and news releases from Tran that accused Steel’s husband, Shawn Steel — former chairman of the California Republican Party — of “selling access” to the Chinese Communist Party.

In one Tran campaign ad that ran on Facebook in September and October, a narrator says in Vietnamese that Steel’s husband “brought Chinese spies into American politics in exchange for money” as the Chinese flag waves in the background. The ad tells viewers that they “cannot trust Michelle Steel to stand up to China.”

The ad refers to a Wall Street Journal story from 2020, which said that Steel’s husband brought several Chinese citizens as guests, including “a man working for China’s central government,” to an “invitation-only gathering” for Republican leaders in San Diego in 2017.

Steel told the Journal at the time that he did not “collect money from, nor have received any funds from” his guests at the meeting.

Steel has loaned her campaign about $1.9 million, financial disclosures show. In July, Tran described her campaign as “buoyed by finances connected to her husband’s dealings with the Chinese Communist Party.”

“Since May, crybaby Derek Tran has leveled false and despicable attacks on Michelle Steel’s family, even putting a CCP flag in his own advertising, but now sobs when our campaign accurately highlights his connections to Communist China,” said Lance Trover, a Steel spokesman.

Tran spokesman Paul Iskajyan said that Tran’s ads are “dealing with facts” and cite published reporting, while Steel’s ads do not.

The imagery and language in the Steel mailer “really preys on the historical trauma that Vietnamese immigrants in this country have,” said Connie Chung Joe, the chief executive of Asian Americans Advancing Justice Southern California, a nonpartisan nonprofit organization.

Representatives of 16 Asian American nonprofit organizations, including Chung Joe and Choi, last week sent a letter to the Democratic Party and Republican Party of Orange County stressing that candidates should dial back rhetoric that “implies falsely” that Asian American candidates are “national security threats.”

“While it is certainly expected that political candidates address geopolitics, and while there are legitimate and serious criticisms of the Chinese Communist Party, imprecise and inflammatory rhetoric can create the false narrative that targets Asian Americans as untrustworthy, anti-American or ‘perpetual foreigners,’” the letter said.

Born to South Korean parents and raised in Japan, Steel broke barriers in 2020 when she became one of three Korean American women elected to the House.

Tran was born in the U.S. to Vietnamese refugee parents. He said his father fled Vietnam after the 1975 fall of Saigon, but his boat capsized, killing his wife and children. Tran’s father returned to Vietnam, where he met and married Tran’s mother, and the couple later immigrated to the U.S.

Tran’s campaign on Monday blasted a recent interview with Steel on the Vietnamese television station VietFace TV, in which interviewer Joe DoVinh told Steel that some people “think that you’re not Vietnamese enough, because you don’t have a Vietnamese last name, and they don’t understand everything that you do for them.”

“I think I am more Vietnamese than my opponent,” Steel responded.

Times deputy editor for culture and talent Anh Do contributed to this report.