WASHINGTON, DC — As the Democratic caucuses kick off in Iowa and the party’s 2020 presidential nomination process gets underway, top candidates are complaining that Independent Sen. Bernie Sanders is pulling in more of their voters than they can muster.

Last week, Sanders managed to pack some 3,000 Democratic voters into a venue near Des Moines, Iowa, while just a few days earlier, former Vice President Joe Biden had trouble filling up a living room.

And recent polling has him tying or topping the leading Democrats.

“You know, this really isn’t fair at all,” complained Biden on Monday as Democrat caucus voters headed to the polls.

“I’ve been a Democrat all my life and a pretty darned good one,” he continued. “Bernie Sanders has never been a Democrat but he keeps thinking he belongs in our party.”

Another top Democrat, Sen. Elizabeth Warren of Massachusetts, agreed.

“It’s one thing to pretend to be Native American,” she told reporters. “For the longest time, until I finally admitted I wasn’t, no one really knew for sure.

“But to pass yourself off as a Democrat when you really aren’t? I mean, how can you people in the press let him get away with that?” Warren continued. “I thought you all were on our side?”

Other leading Democrats also complain that Sanders is intentionally misleading voters into thinking he’s one of them just because he’s running for the party’s presidential nomination.

“I’m angry about it,” said tech entrepreneur Andrew Yang, who has had trouble registering in the polls to begin with. “This was always going to be an uphill battle for me, but I never imagined I’d be losing to a poser.

“Why doesn’t he run third-party like other vanity candidates?” Yang said.

Republicans, meanwhile, are enjoying the controversy, especially President Trump.

Asked before the Super Bowl on Sunday what he thought about Sanders being on the cusp of taking the Democratic Party nomination as a political independent, the president said, “Well, no one thought I could win, either.”