Once again, the American labor movement is giving the strongest possible support to the Democratic candidate for the White House. For decades, Democrats have relied on labor unions for funding and for get-out-the-vote efforts. Hillary Clinton is no different. Most unions supported her in the Democratic primary. Most unions that supported Bernie Sanders have now endorsed her. A few unions, particularly those representing police and firefighters, have endorsed Donald Trump—as has the National Border Patrol Council. But the vast majority is providing Clinton the logistical support that she will need to win the election. But why do unions do this? What do they get from supporting Democrats?

Not only have American unions seen their numbers decline precipitously for the last several decades, but the apparatus of American labor law and regulatory agencies has turned increasingly against workers. Agencies that protect workers’ rights and safety, such as the Occupational Safety and Health Administration, are routinely underfunded while Republican appointees to a wide variety of agencies housed within the Department of Labor, drawn from the ranks of management, have captured the regulatory process to such an extent that leading American union advocates, including former Communication Workers of America president Larry Cohen, have openly wondered whether labor would be better off scrapping the entirety of American labor law if we cannot make it work to protect union rights.

Yet in the last few years, the tenor of American labor regulation has suddenly changed thanks to recent decisions by the National Labor Relations Board (NLRB) that have repeatedly helped improve workers’ rights. The NLRB has reversed a rule that forced so-called “permatemps,” long-term temporary workers, from asking their parent employer’s permission to be included in a bargaining unit for a union election; ruled against employers issuing blanket policies against employees recording violations in the workplace; decided that graduate students at private universities had collective bargaining rights; and reestablished a test to judge whether an employer is hiring permanent replacement workers during strikes. In each of these decisions, President Obama’s NLRB appointees have, arguably, shown a stronger pro-labor record than have those of any President since the agency’s creation in 1935.

This is good news for American workers. But it also reflects the extreme partisanship of the modern United States and highlights to what extent workplace rights are increasingly dependent upon labor electing a Democratic President to office. Congressional Republicans have howled over these recent decisions and nearly every Republican who ran for President this election pledged to reverse them, while also promising to curb this supposedly out-of-control agency. This scenario obviously leads to great instability in workplace relations. But a brief examination of the interaction of state and labor in American history suggests that changes to this fundamentally unstable and deeply partisan relationship are unlikely in the near future.

More than perhaps in any other western democracy, organized labor in the United States has always needed to rely on state support for success. As the sociologist Kim Voss demonstrated in her study comparing employer responses to unions in the United States, Britain, and France in the late nineteenth century, American employers have long taken a much harder line against unions than have their counterparts in European nations, where employers managed to accept unions as central to management decisions. Even today, German unions have a say in corporate management unheard of in the United States, to the point where they effectively forced Volkswagen to support a union organizing campaign in its Chattanooga, Tennessee factory in 2014. Even so, strong opposition from local elites and plant managers on the shop floor convinced workers to reject the union in that vote.

The growth of American industrialization in an era of weak federal government often meant that large corporations had more money than the federal government. The creation of the Federal Reserve in 1913 was, in part, motivated by the government begging J.P. Morgan to bail it out. Not surprisingly then, American employers relied on the state to serve as a police force to bust disruptive strikes, as it did most famously during the Great Railroad Strike in 1877 and again during the Pullman Strike in 1894, in the aftermath of which Labor Day emerged.

Little of this changed until the Great Depression. The intense economic crisis, and the worker uprisings that ensued, helped elect Franklin D. Roosevelt to the White House. The new President quickly ushered in laws to protect workers’ rights for the first time. It was his National Labor Relations Act, passed in of 1935, that created the National Labor Relations Board. Only state intervention that essentially forced companies to agree to collective bargaining with those workers that had organized into a union—and the vast profits generated in preparation for World War II—could produce the conditions in which companies were ready to acquiesce to the existence of unions.

Roosevelt’s advisers intended for the NLRB to be a non-partisan agency; it drew most of its early appointees from government workers. Representing business, labor, and the public equally was in fact a prime goal of many New Deal agencies. The NLRB routinely ruled in favor of unions during these years, leading to conservative members of Congress introducing bills to eliminate the agency. One bill to do so passed the House 258-129 in 1940 before Roosevelt pressured the Senate to kill it. Even with the aim of nonpartisanship, for corporations and conservative politicians, the sheer existence of the agency was an attack on corporate rights.

Roosevelt’s vision of a non-partisan board began to slip during the Eisenhower years, however, when the first member of the business community was appointed. Corporations continued to look to the state to represent its interests over that of workers, even if it had far less power than it did before the New Deal. Unions responded by noting that no unionist had ever served on the NLRB. But corporate America had never accepted the legitimacy of unions, particularly not as an equal counterpart. The Kennedy and Johnson Administration soon after reinstated the tradition of appointing members with no ties to either unions or management. This was, however, short-lived as another Republican, Richard Nixon, would, again, see the board as a partisan agency and name management appointees. But, compared to today, this remained relatively muted through the 1970s.

The modern era of the truly partisan NLRB began in earnest with Ronald Reagan’s first appointee, who was a union-busting management consultant. This was followed later on by a protégé of the staunchly anti-union North Carolina senator Jesse Helms, who had created and distributed both anti-union videos and pamphlets. This broke the façade of neutrality at the NLRB; the Reagan Administration had simultaneously been seeking to gut labor regulations across the board. Bill Clinton was the first President to name union representatives to the NLRB; he appointed three union lawyers, evening out the score while continuing to entrench partisanship. George W. Bush later tilted things sharply back to the right.

Thanks to these developments, by the time Obama took office, the NLRB had become a prime target for congressional Republicans, who chose to filibuster his nominees. It was only after the 2013 break of this filibuster that Obama could finally name his NLRB appointees, who reoriented the agency toward the pro-worker positions that have recently caught headlines.

It is unlikely that the now deep-seated partisanship of the Labor Relations Board will change anytime soon. This is a problem that extends well beyond the board itself; nearly the entire apparatus of government has reached levels of partisanship unseen in a century. The NLRB is most definitely less functional as a partial enforcer of either workplace rights or corporate policy than it would be as a neutral arbiter of a broadly accepted set of basic labor standards. But, then again, American employers and the Republican Party have never actually accepted organized labor as equal bargaining partners. As in the late nineteenth century, American corporations continue to be more intransigent on labor rights than those in either Canada or Europe. This means that elected officials, and, indeed, the results of this upcoming election, will continue to play a disproportionate role in whether we are able to uphold labor rights, or if corporate interests once again gain the upper hand.