Some Senate Democrats are demanding the Senate consider a host of gun control provisions, not just the bipartisan bill commonly assumed to have the best chance of passage. And one of the Democrats who wants a broader debate is Sen. Chris Murphy, the cosponsor of the bipartisan bill.

Between the lines: If Murphy says he won't vote for his own bill — Fix NICS, which would strengthen the existing background check system — without a broader debate, that narrows the chances of a standalone vote on the bill being successful.

Key quote: “I’m not supporting moving forward on Fix NICS without a broader debate. I think that it would be an insult to these kids — these kinds from Parkland, who are here today — to try to avoid having an open debate on the Senate floor on gun violence."

Earlier today, Senate Minority Leader Chuck Schumer said passing Fix NICS alone "would be an abject failure and a dereliction of our duty," and called for universal background check legislation.