Before announcing another bid for the presidency, Joe Biden traveled to Boston to address the striking cashiers, baggers and clerks who belong to the local chapter of the United Food and Commercial Workers International. Their contract dispute with the foreign owners of Stop & Shop wasn’t just about dollars and cents, the former vice president insisted. It was about right and wrong.

“I know you're used to hearing political speeches, and I'm a politician. I get it," Biden said on stage. "But this is way beyond that, guys. This is way beyond that. This is wrong. This is morally wrong, what's going on around this country. And I have had enough of it. I'm sick of it, and so are you.”

One week later, all on the same day, the workers would wrap up their strike, Biden would launch his campaign, and a union-busting lawyer named Steven Cozen would help host a fundraiser for the newest presidential candidate.

The dispute cost the grocery chain a reported $100 million in losses and the political dinner cost donors $2,800 a plate. In the long run, another bill may have to be paid, depending on the answer to this question: Will that kind of two-timing coziness with both labor and ownership cost Biden?

Union bosses backed Hillary Clinton overwhelmingly during the last general election but couldn’t quite deliver enough votes against Donald Trump. Among union workers, the Democrat outperformed the Republican by more than 8 percentage points nationally, a victory to be sure but hardly a sweeping triumph. It was the smallest such advantage since Walter Mondale lost to Ronald Reagan in 1984 and a feeble showing compared to Barack Obama carrying union households by 18 points in 2012.

That weakening may have more to do with Clinton than Trump. The largest federation of unions in the country, the AFL-CIO, found that while 37% of their members supported the GOP nominee, a 4 point increase over support for Mitt Romney in 2012, the 56% who supported Clinton was a 9-point drop from backing for Obama that same year.

Bosses promise to be pickier in the Democratic primary this time around to ensure a better turnout for the nominee in the general election. “With a field this massive, and with everyone scrambling to claim the support of working people, we're in no position to settle. We're looking for a tireless, unapologetic advocate for the labor movement. Nothing less,” AFL-CIO spokesman John Weber told RealClearPolitics.

Branding himself the blue-collar anti-Trump, Biden has done his best to win this bloc of voters. He rallied with the union grocers in Boston. He delivered twin speeches before that to union firefighters and union electricians in Washington, D.C. He will formally kick off his campaign with union steelworkers Monday in Pittsburgh.

United Steelworkers President Leo Gerard will host that event in a local union hall and, while the workers he leads haven’t endorsed, the boss is bullish on Biden.

“Clearly, many of us in the labor movement and in our union are friends with Vice President Biden. He’s been a true supporter of working people and their agenda. He’s someone who we’ve worked with a lot and we all admire tremendously,” Gerard told Politico.

“It would be an understatement to say that our members admire and look forward to working with Vice President Biden. He’s been strong in particular on infrastructure and jobs,” the union boss continued.

Such admiration is made possible in part by the passage of time and a bit of nostalgia. On trade, Biden is to the right of both his chief competitor, Sen. Bernie Sanders, as well as President Trump. As a longtime senator, Biden supported numerous controversial major trade deals including the North American Free Trade Agreement. And as VP, he backed the Trans-Pacific Partnership, the defunct trade agreement that the AFL-CIO said had “failed workers and deserved to die.”

Another possible product of nostalgia: the purported inexhaustible political muscle of labor. While labor has collected political scalps in states like Wisconsin, where it helped knock off Republican Gov. Scott Walker, overall membership in both private- and public-sector unions is dropping. And in states with right-to-work laws, such as Iowa and Nevada, studies find union influence becoming anemic.

Weaker unions translate to weaker Democratic turnout, according to analysis by researchers at Columbia and Boston universities. That study of the 2016 presidential election showed that right-to-work laws stunted Democratic voter share by 3.5% and turnout by 2 percentage points.

Though perhaps a negligible drop-off during a normal election, the researchers argued that the reduction might have denied Clinton victory over Trump, noting that she lost Wisconsin, Michigan, and Pennsylvania by less than a single percentage point in each state.

Some observers believe that low turnout coupled with a sprawling primary field that is increasingly guided by “woke” progressive social policy could sap union strength even more. Looking from the outside in, anti-union crusader Grover Norquist doesn’t see labor as the trump card it was just a few decades ago.

“Identity politics cuts the union membership into little pieces,” he told RCP. “All was fine when [unions] said, ‘We hate the Republicans for different reasons,’ but in a primary they don’t all have the same interests. There are guys who play identity politics, environmental politics, and union politics.”