Late Tuesday night, 11 Senate Democrats joined the Republicans on the banking committee to unanimously approve Ben Carson’s nomination as secretary of the Department of Housing and Urban Development. Even darlings of the progressive left like Elizabeth Warren and Sherrod Brown voted yes on Carson.

Many progressives were outraged. Carson has never run a federal agency, seems unaware of basic details on housing policy, and says he wants to weaken laws that combat housing segregation. Judd Legum, editor of the center-left blog ThinkProgress, shared a headline blasting turncoat Democrats titled “WTF” and captioned it in all caps.

8. BUT A SENATE COMMITTEE VOTED UNANIMOUSLY TO APPROVE BEN CARSON'S NOMINATION. THIS INCLUDED 11 DEMOCRATS. https://t.co/h22NvDUmBn — Judd Legum (@JuddLegum) January 25, 2017

But there’s really no great mystery as to why Senate Democrats decided to back Carson: They simply don’t think he’s a particularly devastating choice for HUD — and they think Trump might replace him with someone far worse if Carson were rejected.

“Carson knows nothing about housing policy, which is pretty bad, but at least he’s shown some respect for the department itself,” said one Senate Democratic aide, speaking on the condition of anonymity.

In contrast, the aide says, Rick Perry, Trump’s choice for the Energy Department, once said he wanted to get rid of the department altogether. Trump’s Environmental Protection Agency nominee, Scott Pruitt, is currently suing the EPA.

Carson has never similarly vowed to demolish HUD itself, the aide says. “Most people think [Carson’s] just not as crazy — that he's a smart person who doesn't have the qualifications, but would respect the office. And that's not the case with these other nominees.”

Grassroots progressives are agog at Senate Democrats’ decision

Yet to much of the left’s grassroots base, voting for Carson looks like an unforced act of capitulation to the enemy.

Carson may not be Trump’s most conservative nominee, but he’s expressed some views deeply at odds with what the Democratic Party purports to stand for. There was the time Carson compared same-sex marriage to the North American Man-Boy Love Association. He’s called President Obama “the worst thing since slavery.” He has said that a Muslim “should not be in charge of this nation,” expressed views condemned as deeply Islamophobic, and blamed the victims of the Oregon shooting that left nine dead for not moving on the killer. The list of outrages goes on.

Ben Carson openly said that he was against constitutional rights for Muslims - and Dems are voting him in. — Imraan Siddiqi (@imraansiddiqi) January 24, 2017

As the Huffington Post notes, progressives across the country are hungering for their leadership to stand up to Trump. Over the weekend, more than 3 million protesters took to the streets all over the country to oppose Trump as part of the Women’s March. Liberals have talked of fomenting “the resistance” to Trump, and backing his Cabinet nominee appears to contradict that.

Then there’s the additionally confounding fact that Carson was going to be approved with or without any Senate Democratic votes, since Republicans only need a simple majority for all Cabinet positions. Since Democrats don’t have the ability to actually block Carson, it would seem they could make a symbolic statement against the Trump administration by voting no on Carson without crippling the government and depriving it of an agency head, as Matt Yglesias argued. But even progressives like Warren and Brown chose not to do this.

The disconnect between the grassroots and Capitol Hill

The story inside Capitol Hill is very different from what you hear from the party’s grassroots.

Senate Democrats, who have spent weeks in hearings and meetings evaluating Trump Cabinet nominees, say they’ve been surprisingly impressed by Carson — both in his written answers to the banking committee and in the one-on-one interviews they conducted with him before his hearing.

They admit the bar is low but say Trump’s HUD nominee has cleared it relative to Trump’s other picks. “I think some of these members in these private meetings, they were not terrified by him,” another Senate Democratic aide said.

Among the Carson statements they’ve highlighted:

To the surprise of some Senate Democrats, Carson promised to enforce lead standards and work with “bipartisan” experts on how to reduce rates of lead poisoning.

In his written statement, Carson also said he would “without hesitation” enforce HUD’s Equal Access Rules, which ensure gay and lesbian housing applicants aren’t discriminated against in their housing applications.

Carson also promised to advocate for investments in rental assistance for the homeless, and to advocate that spending for housing be part of the infrastructure program Trump has promised to implement.

Now, Senate Democrats are being sure to explain that Carson is not their ideal choice. But they’re arguing that voting for him will make him more likely to listen to what they want, and make it easier to call him out if he breaks those pledges.

“Carson is not the nominee I would have chosen to lead HUD,” said Ohio’s Sherrod Brown in a statement. “But despite my reservations ... I will give Dr. Carson the benefit of the doubt based on commitments he has made to me in person and to this Committee in his testimony and written responses.”

Massachusetts’s Elizabeth Warren has also taken significant heat from the left for backing Carson. In an email, a Warren spokesperson also pointed to Carson’s written answers to the senator’s questions, including his pledge to “strongly support” existing homeless reduction programs.

There’s also the strong institutional pull for Democrats to follow historical precedent and let the president choose his Cabinet nominees. In its history, the Senate has only voted down nine presidential Cabinet nominees, according to Josh Huder, a congressional scholar at Georgetown. Almost all of President Obama’s picks sailed through in 2009 without much resistance. And that was at a time when Republicans in the minority could still filibuster them — meaning they could have blocked them, but didn’t.

“We can’t very well be at a fever pitch on everything,” Sen. Brian Schatz, a progressive Democrat from Hawaii, told the Huffington Post. “The door swings both ways in Washington. At some point we’re going to want a Democratic president to stand up a Cabinet. So we’re trying to be reasonable when the nominees are reasonable.”