Washington CNN  — 

President Barack Obama’s chief of staff is crediting Vermont Sen. Bernie Sanders with “some movement” on guns in recent days – and made clear Obama is watching closely.

In an interview with CNN’s Jake Tapper on “State of the Union” Sunday, White House chief of staff Denis McDonough credited Sanders for shifting to the left on gun control.

“As it relates to Sen. Sanders, we’ve seen some movement on this since the op-ed appeared on Thursday. We think that’s good. If that continues, that’s the goal of this, is making sure that we have gun laws that are responsive to the wishes of the American people, not responsive to the big NRA bosses here in Washington,” McDonough said.

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Obama said in a New York Times op-ed that he won’t campaign for or vote for anyone – Democrat or Republican – who doesn’t support “common-sense gun reform.”

McDonough’s comments Sunday signaled that the President’s move was aimed at least in part at pressuring Sanders on the issue.

Sanders has taken heat from Democratic rival Hillary Clinton on gun control. She has lambasted his vote for legislation that would protect gun manufacturers from liability when their guns are used in a crime.

“Maybe it’s time for Sen. Sanders to stand up and say, ‘I got this one wrong,’ ” Clinton said Friday on MSNBC. “When it really mattered, Sen. Sanders voted with the gun lobby, and I voted against the gun lobby.”

Sanders, meanwhile, has said he is willing to reconsider his vote for that legislation. He has defended himself against attacks over his gun votes by pointing out that his rural state, Vermont, has some of the nation’s most lax gun control laws.

McDonough said Obama will wait – and see how the gun debate plays out – before endorsing a candidate in the 2016 race.

“As we see it, we’ll make some final decisions about what the President will do and who he’ll support,” McDonough said.

McDonough was also asked whether Obama might support a third-party presidential run by former New York City Mayor Michael Bloomberg, who has made gun control a focus and is said to be considering a run.

But McDonough deflected, saying, “That sounds to me like a hypothetical built on a hypothetical.”