Washington DC - International Brotherhood of Teamsters General President Sean O'Brien gave fiery testimony on corporate greed in a Wednesday Senate hearing which put growing class tensions on full display.

O'Brien appeared alongside fellow labor leaders Liz Shuler, AFL-CIO president, and Mary Kay Henry, SEIU president, to testify before the Senate Health, Education, Labor, and Pensions (HELP) Committee, chaired by Senator Bernie Sanders.

The hearing, entitled Defending the Right of Workers to Organize Unions Free from Illegal Corporate Union-Busting, sought to highlight the gross levels of economic disparity in the United States and emphasize the need for greater labor protections.

"The percentage of American workers who support unions is at an all-time high, but they're unable to join unions, form unions, or get a first contract because in America, the game is rigged," O'Brien said in his remarks.

Donald Trump Trump announces former ICE director who pushed for family separation as "Border Czar"

The Bostonian pointed out that union workers make more than their non-union counterparts on average, and that unions can help drive up wages across industries. Despite that, weak US labor laws allow companies and CEOs to get away with violating workers' right to organize without facing any meaningful consequences.

The lifelong Teamster also called out the senators who have co-sponsored the National Right-to-Work Act, reintroduced by Kentucky Republican Rand Paul in February, which would further chip away at workers' ability to wield their collective power.

"Instead of supporting legislation to protect workers' choice to join a union, half the senators on this committee are only willing to offer right-to-work laws. These deceptive laws allow workers the right to leave a union while still reaping all the benefits of belonging to one," O'Brien explained.

"When any employer, be it the rail companies, package companies, or coffee shops, gets away with repeated abuse of American workers, the legislators who make it happen are complicit in these crimes," he added.

While the partisan divide on workers' rights was clear throughout the hearing, things got even more heated when Republican committee member Markwayne Mullin took the mic with a personal axe to grind.

The junior senator from Oklahoma insinuated that unions are more to blame for worker intimidation than employers.

Mullin spoke about his own experience as the previous owner of five non-union plumbing companies and accused Teamsters members of engaging in threatening behavior, picketing job sites, and staking out his home in 2009 in order to scare workers into joining a union.

Donald Trump Russia responds to reports of Trump-Putin call and hints at stance towards new administration

The Tulsa-born politician then began to attack O'Brien's salary and complained that he was "sucking the paycheck out of somebody else" – comments the Teamsters president called "out of line," which then drew an aggressive response from Mullin: "You need to shut your mouth."

"We hold greedy CEOs like yourself accountable," O'Brien retorted. "You want to attack my salary, I’ll attack yours. What did you make when you owned your company?"

The multimillionaire claimed he kept his salary at $50,000 a year. He made the statement in spite of well-publicized controversy over the more than $600,000 he allegedly took from the plumbing companies in violation of federal law and House ethics rules in 2013.

Mullin transferred ownership of the companies to his family but stayed on as a board member and chief advertiser while raking in the dough. After selling the companies in 2021, his net worth ballooned to between $31.6 million and $75.6 million, up from $7.3 million-$29.9 million at the end of 2020.

"This shows their behavior on how they try to come in and organize a shop," Mullin said, pointing his finger at the three labor leaders, to which Sanders responded, "They show your behavior. Stay on the issue, please."

The tense exchange brought to the fore fundamental divides in US society today, which is seeing the ultra-wealthy consolidate even more money and power while an increasing number of Americans struggle to make a living.

As he wrapped up the session, Sanders pointed out that one of the most powerful ways to win better wages and benefits and reduce those gross disparities is through union organizing.

"There's a class war going on, whether we want to recognize it or not," the senator insisted.

"People on top have the money, they have the power. They're spending hundreds of millions of dollars to try to prevent ordinary workers from coming together to fight for dignity," he continued.

"Don’t let them distract you. Unions create jobs, make work safer, and put more money in workers’ pockets. Most importantly, everything we do is to improve the lives of our members… I wonder if some others can say the same about their constituents?" O'Brien tweeted after the hearing.