I recently attended a political rally in my hometown of Minneapolis, where U.S. Sen. Bernie Sanders of Vermont and Minnesota U.S. Rep. Keith Ellison fired up a crowd of several thousand in support of progressive candidates in this year's elections.

I yelled, I cheered and I left the rally feeling energized, confident that politicians who share my values have a fighting chance this fall.

Yet within several days, this excitement had turned to frustration. That's because the base of the party with which I've historically been aligned — the Democratic Party — can't keep its eye on the prize.

Consider: This past Saturday night, while Democrats might have focused on the president's disastrous trip abroad, they instead had their fire trained on Elon Musk. This would be the same Elon Musk who founded an auto company dedicated to a zero-emission future, forced other major automakers to follow in his footsteps and backed up this commitment with big donations to the Sierra Club.

His sin? Mr. Musk, through one of his companies, made a sizable donation to a Republican PAC.

It's not the first or even the 50th way I'd choose to spend my own money. But it's not unusual for corporations like his to make donations to both parties. And I can sleep well at night knowing that, whichever climate-change-denying candidates Musk's GOP largesse might support, it is dwarfed by the good the Sierra Club can do with his contributions.

Apparently, I'm in the minority with this viewpoint.

This isn't the only time in the past week that the party faithful — my party faithful — have let me down. I'm a bartender by trade, and I've been a staunch supporter of raising the minimum wage for restaurant workers. But I'm an equally strong supporter of the country's current tipping system, which puts me at odds with a vocal faction of the progressive base, who'd like to see it eliminated.

Even friends have disagreements — but this past week, these "friends" accused a diverse coalition of workers and politicians in Washington, D.C., who are trying to save the tipping system, of black voter suppression.

Voter ID laws suppress the black vote. Gerrymandering electoral districts suppresses the black vote. Politicians who are standing up for tipped workers of color most certainly are not suppressing the black vote.

These are just two examples — I could name others. The common theme here is that progressive activists around the country are attacking allies over a failure to pass arbitrary purity tests, rather than building lasting coalitions that can cement progressive gains at the state and federal levels. I've grown so frustrated by this infighting that I've stopped calling myself a Democrat; currently, the term seems to require blind allegiance to policies, candidates and coalitions that don't always match my own beliefs.

I'm 31 years old — just a few years older than another bartender, Alexandria Ocasio-Cortez, who recently won the Democratic nomination for a House seat in New York City. I don't know whether her values perfectly match my own; frankly, I don't care.

None other than Ronald Reagan once said that the person who agrees with you 80 percent of the time is a friend and not an enemy.

If the Democratic Party wants to govern again, it would do well to take a lesson from him.

Jennifer Schellenberg is a bartender in Minneapolis and founder of Restaurant Workers of America.