Sen. Bernie Sanders’ presidential campaign has seen a huge drop in donations since former Vice President Joe Biden entered the race, and he’s begging donors to “dig a little deeper.”

In a long email promising to undo President Trump’s actions if elected, Sanders' campaign manager Faiz Shakir revealed that the average donation to the Vermont senator’s operation has been cut in half.

“I’m about to ask you to make a contribution, and I hope that it is clear why. But first, I want to be up front with you that our average contribution — which used to be $27 — has been almost half that in the last couple weeks. It’s OK for now, but we would really like to see if you can dig a little deeper if you’re able to,” he wrote.

In the campaign so far, just like in 2016, the Sanders campaign has been an online fundraising juggernaut. He raised $18 million in the first quarter of 2016, topping every other Democrat in the race at that time. Biden joined the race April 25.

The email seeks a donation of $3, though it also includes amounts of $27-$1,000 on the donor page.

Since Biden entered the race, the media focus and even Trump have turned to the former vice president and away form Sanders. Many analysts and pundits have suggested that Biden would be a better pick for the Democrats to beat Trump.

In his memo, Shakir rejected that and said only Sanders could both beat Trump and reverse his actions in office.

He twice called Trump an “aberration” that needs to be erased.

“We’re not going to be afraid to call out parts of the establishment that think what we’re doing is too radical. We know that Donald Trump is not just an aberration — he is a logical conclusion of a corrupt political system that has left so many people so far behind,” said Shakir.

“If all we do in this moment is try to turn back the clock to a pre-Donald Trump time in Washington, D.C., we will have failed. That is simply not good enough. And we will make clear both during this campaign, and after we win during the fight to implement our agenda, that it is time for a new way of thinking,” he added.