With President Biden expected to join a picket line on Tuesday, a new survey finds that support for the striking United Auto Workers has increased since the strike began as politicians from both parties move to align themselves with the striking union members.

A new survey by a liberal pollster, Data for Progress, suggests that 62 percent of those surveyed support the striking union members compared to 29 percent who oppose the strike. Support was most widespread among Democrats, with 79 percent saying they support the union’s strike compared to just 13 percent who oppose the strike. 

Among independents, 59 percent said they support the strike, and 31 percent said they did not support the strike. Among Republicans, 48 percent said they support the strike compared to 45 percent who oppose the strike.

The pollster also found that support for the strike has expanded as it has gone on. Their latest survey, ending on September 21, found that 62 percent reported supporting the strike, whereas an earlier survey from September 15 found that 55 percent supported the strike.

The newer survey was of 1,229 likely voters and had a margin of error of plus or minus 3 points. The survey comes as politicians from both parties look to capitalize on the popularity of the strike.

The results of the survey appear to reflect the popularity of unions in general in America. According to Gallup’s annual survey on the topic, support for unions was at 67 percent in 2023, near the historic high of 71 percent in 2022 and up from an all-time low of 48 percent approval in 2009.

Mr. Biden is planning to join a picket line in Michigan on Tuesday, saying he’s going to “stand in solidarity with the men and women of UAW as they fight for a fair share of the value they helped create.”

“It’s time for a win-win agreement that keeps American auto manufacturing thriving with well-paid UAW jobs,” Mr. Biden said.

The president’s visit follows an appearance on a picket line by the populist Republican senator from Missouri, Josh Hawley, who on Monday visited a picket line of UAW members on strike at Wentzville, Missouri’s General Motors plant. The senator’s intention was “to stand with them and protect American jobs,” his office said.

“These workers deserve better pay, better benefits, and a GUARANTEE their jobs will stay in America,” Mr. Hawley later tweeted, adding “These companies are making billions in profits – and spending billions on idiotic ‘climate change’ initiatives that make China rich and kill American jobs.” He instead suggested the companies “spend that money on American workers.”

President Trump has also broken with Republicans’ traditional antagonism toward organized labor, releasing a radio ad at Detroit and Toledo saying that he “always had their back” in reference to the striking union members.

The two men have received markedly different responses from the union as well. While the UAW president, Shawn Fain, invited Mr. Biden to attend a picket line, he specifically said Mr. Trump would not be welcome. Other union leaders like the UAW regional director in Ohio and Indiana, Dave Green, have also taken issue with Mr. Trump’s claims.

“Just look who Trump put in the courts,” Mr. Green told the Associated Press in response to Mr. Trump’s new ad. “Look at his record with the labor relations board. He did nothing to support organized labor except lip service.”

Mr. Trump’s rhetoric around the UAW strike has still been far friendlier to the striking union members than his Republican predecessors and even some of his opponents in the GOP primary, who have traditionally been opponents of organized labor.

Some Republicans on the campaign trail have invoked Ronald Reagan’s firing of some 11,000 striking air traffic controllers in 1981 as an example of how Republicans should approach striking unions.

“Ronald Reagan gave us a great example when federal employees decided they were going to strike. He said, ‘You strike, you’re fired,’” adding that it’s a “simple concept to me,” Senator Scott said when asked about the issue by a voter.

According to the survey, Mr. Biden is seen as more credible in his support for unions than Mr. Trump. The survey found 44 percent of respondents trust Mr. Biden more to support labor unions, while 29 percent support Mr. Trump, and 21 percent of respondents said  “neither.”

Broken down by party, 77 percent of Democrats and 36 percent of independents said they trusted Mr. Biden more to “support labor unions.” For Mr. Trump, 58 percent of Republicans and 22 percent of independents trusted him more to support unions.

A political scientist and pollster at East Carolina University,  Peter Francia, found that Mr. Trump’s relative popularity among union households was a key to his 2016 victory, and a decline in his popularity among union households was important to his 2020 defeat.

“By expanding previous Republican margins with white working-class voters and by narrowing the Democrats’ typical union household advantage, Trump secured himself victories in Pennsylvania, Michigan, and Wisconsin, which ultimately won him the election,” Mr. Francia wrote.

According to the Cornell Roper Center for Public Opinion Research, Mr. Trump carried the support of 43 percent of union households in 2016, compared to 40 percent in 2020. In 2016, Secretary Clinton carried 51 percent of the vote among union households, whereas Mr. Biden carried 56 percent. 

For comparison, President Obama carried the vote of 58 percent of union households, whereas Mr. Romney carried the support of 40 percent of union households in 2012. In 2008, 59 percent of the union household vote supported Mr. Obama, and 39 percent supported Senator John McCain. 

Economically,  some groups, like the Anderson Economic Group, have estimated that a ten day strike of the full union membership could result in a nationwide loss of $5.6 billion, including some $859 million in lost wages for auto employees.

The current model of strike the UAW has adopted, however, only targets some facilities, meaning the overall nationwide loss due to the strike is likely lower.