Does Trump think Muslims should be banned from Congress? The White House isn't sure.

The question was first posed to White House press secretary Sarah Sanders in September, after Moore won the GOP primary in Alabama. It became relevant again, in this setting, when Trump on Monday formally backed Moore ahead of next week's vote.

"Given the President's endorsement," a reporter asked, "does he agree with Roy Moore that Muslims should not be able to serve in Congress?"

Moore in 2006 wrote an article headlined, "Muslim Ellison Should Not Sit in Congress." It compared the decision by Rep. Keith Ellison, D-Minnesota, to be sworn into office with his hand on the Quran to a (hypothetical) new member choosing, in 1943, to "take their oath on Mein Kampf."

"I haven't asked (Trump) about past statements from Roy Moore," Sanders said on Tuesday.

Pressed, she added: "I'm saying (Moore) supports the President's agenda; the President doesn't necessarily support everything of Moore's agenda."

The interaction, stripped of the particulars, was familiar enough. Reporter asks question. Spokesperson either doesn't know answer or doesn't want to give it. Ambiguity remains. Rinse, wash, repeat. But it was the subject matter here that made Sanders' reply so jarring.

Does the President of the United States believe Muslim people should be banned from serving in Congress? That's one where, even if they never discussed it, you'd hope the White House press secretary would feel comfortable jumping out on a limb and saying, "No."

Alas.

Mix in some more context -- specifically, candidate Trump's call in December 2015 for a much wider ban on Muslims -- and the White House's refusal to offer a clear response, twice over, becomes more difficult to brush off.

None of this is to say that Trump does, in fact, agree with Moore. The President didn't support him in the Alabama primary. And he took a while to make public his backing ahead of next week's special election.

In September, after Moore won his primary, Sanders seemed to say that Trump was not on board with some of Moore's most disturbing past remarks. When the Ellison comments were listed among them, and a reporter asked if Trump "share(s) any of those views," Sanders said he didn't -- at least "not that I'm aware of."

"I have not taken a deep dive on every comment that the senator -- or the Senate nominee -- has made, but I certainly know where the president stands on those issues and wouldn't see any parallel between the two of them on that front," she added.

A few minutes later, a reporter asked if she wanted to "condemn some of those sentiments that you said the President, to your knowledge, does not share?"

"I would certainly say we don't agree with those comments," Sanders responded.