Kristen Welker is now at the helm after Chuck Todd stepped down, and her first show Sunday featured a lengthy interview she did with the former President ... and it contains an interesting soundbite where she asks him about his refusal to accept the election results.

Check out this exchange ... Welker points out that Trump has repeatedly said he only needed a few thousands votes in each state to win -- not to mention calling some Secretaries of State in an attempt to pressure them to "find" votes -- and he acknowledges that's true.

Then Welker asks the obvious ... "When you say you needed one-tenth of a point, you needed one-tenth of a point to win?" Trump concedes he needed only a smattering of votes.

She again presses ... "To win?" DT responds, "Yeah." Welker then goes to the next obvious fact here ... "But Mr. President, you’re saying you needed more votes to win the election, are you acknowledging you didn’t win?" That sends Trump into an "Excuse me" frenzy.

When she finally asks him if he's admitting to losing ... he says no, insisting it was rigged.

There are other interesting takeaways from the sit-down ... including Welker asking Trump if he fears going to prison. He tells her no, because apparently, he doesn't even think about it.

Now, we should point out ... Welker/NBC is catching a bit of flak over their decision to interview Trump at all and to give him a "platform." That's silly, though -- the guy is headed toward becoming the Republican nominee, and he continues to be newsworthy. 🤷🏽‍♂️