It’s been three years since Donald Trump was elected president, and Democrats had all this time to find a good candidate to challenge him. They didn’t deliver.

Barely a majority of Democrats, just 51%, believe that Joe Biden is likely to beat Trump, according to a recent Gallup poll. For Bernie Sanders and Elizabeth Warren, the numbers tumble to 16% and 15%, respectively. Democrats are none too confident in their own.

Even billionaire and long shot presidential candidate Michael Bloomberg understands the problem. After announcing his campaign for president, Bloomberg justified his vanity project by arguing that Trump has a better chance of election in 2020 than he did in 2016.

Bloomberg claimed that he is the candidate to fight the “existential threat" of Trump, but the former New York City mayor won’t be the one to beat the sitting president. Bloomberg is “the most disliked candidate in the race,” according to a recent Morning Consult survey. Despite having 88% name recognition, Bloomberg is polling at just 2%.

The real problem for Democrats isn't Bloomberg. It's that their front-runners might not be able to dump Trump either.

"Right now, Donald Trump is winning. He is winning that election," Bloomberg’s campaign manager Kevin Sheekey told CNN this week. "It’s very tough for people who don’t live in New York or California to understand that, but that is what’s happening.”

It’s almost like America has forgotten what happened in 2016. It’s not enough to attack Trump for his character, his tweets, or his bad policies. Democrats have to nominate someone sane enough to win over swing voters. It might be a bridge too far.

With Warren’s and Sanders’s aggressive taxation plans , it’s no wonder Democrats are afraid for the candidates' chances in a solid economy . More moderate than his peers but too timid to talk over them at the Democratic debates, even Biden is losing ground . The fact that Bloomberg picked this week to jump into the race is telling.

Despite years of Russia investigations and months of impeachment proceedings, Trump’s approval rating hit 43% this month — five points higher than on the day he was elected. As an incumbent, albeit a chaotic one, he holds a massive advantage . But that doesn't mean he can't be beaten.

All the Democrats have to do to win in 2020 is to nominate someone reasonable. It just doesn’t look like they’ll be able to do it.