Updated at 1:45 p.m. Monday to clarify Cruz comments from primary night.

WASHINGTON — Even before polls closed on primary day in March, Sen. Ted Cruz had already called his opponent the "S" word.

"I am not remotely afraid to debate left-wing liberal socialists," he said, referring to Rep. Beto O’Rourke and Sen. Bernie Sanders.

The El Paso Democrat, unlike the Vermont senator, says he isn’t a socialist, though, and independent experts agree.

“Cruz can call him anything he wants,” said Peter Dreier, a professor of politics at Occidental College who has written extensively on socialism in the United States. “But if he calls him a socialist, then he doesn’t know very much about socialism.”

This election cycle, some Texas Republicans have taken to slapping the label “socialist” on Democratic opponents who do not identify as socialists. The campaign of U.S. Rep. Pete Sessions of Dallas said challenger Colin Allred has “socialist ideas.” A campaign email from Chip Roy, a former Cruz chief of staff running for a vacant San Antonio-area congressional seat, compared Joseph Kopser to Karl Marx.

The accusatory rhetoric isn’t limited to Texas, and it isn’t a recent phenomenon. Politicians have been accusing opponents of being Marxists or socialists for decades. But since Sen. Sanders’ run for president brought what he calls “democratic socialism” into the mainstream, some progressive Democrats have adopted democratic socialist policy demands, and Republicans are capitalizing on that transfer of ideas.

“There’s no need to freak out about this. This is not the coming of Soviet politics to America,” said David Azerrad, a Heritage Foundation fellow and politics scholar.

Socialism defined

The meaning of “socialism” is messy, to say the least.

The Marxist-Leninist definition of a socialist society is worker ownership of the means of production. Marx used the terms communism and socialism interchangeably in his writings. Vladimir Lenin distinguished the two. For him, socialism was a stepping-stone to communism, and the transition would be complete when the government was completely dissolved.

During the Cold War, socialism was associated with countries such as China, the Soviet Union, North Korea and Vietnam. Cruz’s father immigrated to the United States from Cuba and was an early Fidel Castro sympathizer who quickly soured on the communist regime. The Cruzes, father and son, share a deep mistrust of communism.

Sen. Ted Cruz and other Texas Republican candidates for Congress have called their opponents socialists. Experts say it isn't true. (Smiley N. Pool / Staff Photographer)

American politicians notoriously exploited fear of communist and socialist ideas to attack opponents during the Red Scare of the late 1940s and early 1950s.

In his 1950 U.S. Senate race in California, future President Richard Nixon, then a congressman, accused his Democratic opponent, fellow U.S. Rep. Helen Gahagan Douglas, of communist sympathies. He had campaign fliers printed on pink sheets of paper and called her "pink right down to her underwear." Nixon won.

For many Americans, particularly younger voters, Sanders’ run for president erased the stigma. Socialism is not necessarily a dirty word anymore. But some socialists question whether Sanders is really one of them.

As mayor of Burlington, Vt. Sanders called himself a socialist. He has long had connections with socialist organizations. But he has renounced key elements of socialism. In November 2015, he said he didn't believe that "government should own the means of production" but did think "that the middle class and the working families who produce the wealth of America deserve a fair deal."

Mimi Soltysik, the Socialist Party USA’s presidential candidate in 2016, said Sanders’ rhetoric does not match up with the socialist belief in a classless society.

“Socialism is not about strengthening the middle class. It’s about a complete opposition to the class-based system,” he said.

Experts say Sanders is better described as a “social democrat” who advocates limiting corporate influence and expanding the social safety net without overthrowing the capitalist system.

“Nobody is calling for people to take over Walmart and Disneyland. Nobody,” Dreier said. “It’s a mild form of what the Europeans call social democracy.”

Sanders’ brand of democratic socialism is inspired by Scandinavian countries instead of the Soviet Union, and it has resonated among young voters. A Gallup poll published Aug. 13 found that among respondents ages 18 to 29, 51 percent held a positive view of socialism, while 45 percent had a positive view of capitalism.

Nationally, membership in the Democratic Socialists of America has jumped from 6,000 in November 2016 to more than 40,000 members this year. The DSA's North Texas chapter was founded in April 2016 with 150 members and has grown to 500, according to co-chair Kristian Hernandez. The organization has also expanded into Fort Worth, Collin County and Denton County, and it is holding interest group meetings in Tyler.

Rick Treviño, a self-described democratic socialist who lost the Democratic primary to Gina Ortiz Jones in Texas’ 23rd Congressional District, said attacks using the “socialist” label resonate most with older, conservative Republicans.

“If your base is older, those labels mean something," Treviño said. "To younger people, they don’t have the baggage of growing up in the Cold War."

So who is right about the meaning of socialism: the Soviets, or Sanders?

Azerrad said both are correct.

“It’s a question of linguistics," the Heritage Foundation scholar said. "Words have meaning, but language is living and changing, and the meaning of the word has changed over time.”

While the left sorts out how to define democratic socialism, Republicans have seized on the loaded “socialist” label.

Tensions bubbled over in the Maryland governor's race early this month when Democratic candidate Ben Jealous used an expletive when asked if he identified with the term "socialist," as his Republican opponent had dubbed him.

For Cruz, Sessions and Roy, it's likely the accusatory rhetoric is an attempt to stoke their bases in competitive midterm races.

“It’s an activation game, and you can see in Texas that you have half the turnout in the midterms. You have to make sure to get voters not to skip,” said Guy Harrison, a partner at OnMessage Inc. who formerly served as executive director of the National Republican Congressional Committee and as Sessions’ chief of staff.

The Sessions and Roy campaigns have doubled down on their claims that their Democratic opponents are socialists, largely based on their support of health care reform.

When asked to explain the label, Sessions’ chief of staff, Caroline Boothe, said in a prepared statement that Allred had proven his socialist credentials by supporting expansions of the Affordable Care Act, Medicaid and Medicare, which Boothe characterized as “a complete government takeover of health care in our nation.”

According to a policy brief provided by the Allred campaign, he does not support a “government takeover” but instead favors letting all Americans buy into Medicare for health insurance coverage, not universal coverage.

On Monday, the Cruz campaign backed off the use of the word "socialist" to describe O'Rourke, and instead pinned the label on O'Rourke's support for universal health care.

The night of the March 6 primaries, Cruz referred to his challenger as a socialist in a call with reporters, when asked if he would debate O'Rourke during the campaign.

"Listen you're talking to somebody who last year went three times on CNN and debated Bernie Sanders. I am not remotely afraid to debate left-wing liberal socialists. And the values of Texas are not the values of Congressman O'Rourke or Bernie Sanders or Elizabeth Warren or Chuck Schumer," Cruz said.

But on Monday, Cruz campaign spokeswoman Emily Miller insisted that Cruz was only referring to Sanders, though he has offered the same formulation many times.

"I don't know whether Beto considers himself a socialist or not -- I don't know that he's ever been asked that -- although he certainly supports socialized medicine," she said. "Regardless, Sen. Cruz was referring to Bernie Sanders, who unlike many Democrats is open and fully admits he's a socialist."

O'Rourke said he does not identify as a socialist.

"I don't know about labels," O'Rourke said. "I just know that Texans expect us to put the business of running this country first."

Regardless, Soltysik, the Socialist Party USA's former presidential candidate, said even unabashed support for universal health care does not make a candidate a socialist.

“It would be one policy that you would see under a socialist program, but it’s one of many,” he said.

Franklin Bynum, a Democrat seeking a criminal court judgeship in Houston, is among more than a dozen democratic socialists who have run for office in Texas this year. He said he doesn't mind Republican attacks calling him a socialist and isn't offended by others who decline to identify with the term. The Harris County Republican Party recently tweeted a dramatic, heavily edited photo of Bynum superimposed over a hammer and sickle.

“Far-right, reactionary Republicans have nothing to say except that they are running against a socialist. I think that’s great,” Bynum said.

Transfer of ideas

While O’Rourke, Allred and Kopser are certainly not socialists by the Marxist-Leninist definition, each candidate has adopted positions from Sanders.

Sanders ran on an extensive platform including taxing top earners, universal health care, tuition- and debt-free college, removing corporate money from politics, a $15 minimum hourly wage and other positions that supporters consider progressive.

Among the Sanders planks that O’Rourke adopted are universal health coverage, debt-free college education for some students, and ending the federal ban on marijuana. He also has made opposition to corporate influence in politics a hallmark of his campaign.

Unlike Sanders, O’Rourke isn’t pushing for tax hikes on the wealthy, and while he supports a “living wage,” he doesn’t specify a dollar amount.

Allred’s platform features scaled-back versions of some of Sanders' proposals. He supports Medicare availability for all, campaign finance reform, debt-free college for families earning less than $125,000, raising the minimum wage to $15 an hour and legalizing medical marijuana.

Allred spokesman Hector Nieto said the candidate “believes in capitalism, not socialism,” and he dismissed the accusations as “name-calling.” He also said that many of Allred's positions are consistent with those of mainstream Democrats.

Kopser supports universal health care, “affordable” college and raising corporate income taxes. He also said he does not identify as a socialist. And in a prepared statement, he called Roy’s rhetoric “politics of division."

The Democratic candidates have not identified themselves as socialists, but Kristian Hernandez with the North Texas Democratic Socialists of America said she was heartened to see some of the DSA’s policy demands being adopted by mainstream Democratic candidates.

“Their win could help expand causes like Medicare for all and ending mass incarceration," Hernandez said. "We are in favor of policies that will benefit working-class people.”

Republican strategist Guy Harrison said that if Democrats are going to call socialist labeling a “scare tactic,” they should “stop standing with people who are socialists, and stop spouting the policies.”

“These candidates have actively gone further and further left to try to get clicks and online progressive money to fund campaigns,” Harrison said. “You can’t go both ways.”

Correction, 6 p.m. Aug. 21: An earlier version of this story incorrectly stated that Sen. Ted Cruz called Rep. Beto O'Rourke a "Bernie Sanders-style liberal socialist" the night of the March 6 primaries. Cruz did not use that phrase. Asked whether he would debate O'Rourke, Cruz told reporters that "You're talking to somebody who last year went three times on CNN and debated Bernie Sanders. I am not remotely afraid to debate left-wing liberal socialists."