Washington (CNN) Senate Majority Leader Mitch McConnell did not consult with the White House when he and House Speaker Nancy Pelosi planned to invite NATO's secretary general to speak before Congress on Wednesday -- a move that multiple congressional and diplomatic sources say they view as a rebuke to President Donald Trump.

NATO's Jens Stoltenberg is set to give a rare address to a joint meeting of Congress as the trans-Atlantic alliance celebrates its 70th anniversary this week.

One Republican source on Capitol Hill confirmed to CNN that there was no consultation between McConnell and the White House in the decision to plan Stoltenberg's address, adding, "Why would there be?" since the leaders of each house of Congress are the ones who must agree to invite a guest to speak.

But multiple sources said they view McConnell's move as a remarkable rebuke to all of Trump's ringing criticism of NATO over the years and his suggestion that NATO countries double their defense spending to 4% from 2% of their country's gross domestic product.

The White House did not immediately respond to a request for comment.

On Tuesday, Trump hosted Stoltenberg at the White House and praised the NATO chief's job performance as "outstanding."

"The relationship with NATO has been very good, the relationship with the secretary general has been outstanding," Trump said while seated next to Stoltenberg in the Oval Office.

But Trump slammed NATO as "obsolete" just after he was elected, alarming allies who were then criticized by the American President for not spending as much as Trump thinks they should on defense. Trump has since spoken of the importance of the alliance, but recent reporting by The New York Times stated that Trump had privately threatened to pull the US out of NATO, bringing this idea up with aides multiple times, as recently as last year.

All the more reason for members of Congress to want to show the world their support of the institution, sources told CNN, even if the President's support has been uncertain at best.

"No doubt it is (a rebuke)," one senior Democratic aide told CNN. "It is a big deal. The President is not on the same page as his party on this. The foreign policy of the Republican Party is not in the same place as him. It is a rebuke of this administration and its policies (on NATO)."

A spokesman for McConnell defended the majority leader's involvement in inviting Stoltenberg to address Congress and denied it was a reaction to Trump's statements about NATO.

"This is not a rebuke," David Popp said, adding that McConnell "has been clear on his support for NATO for a number of years."

Popp said that the decision to have the NATO secretary general speak was "Congress speaking to more than the White House."

"We operate on our own terms. He's never projected this specifically to the White House," Popp said. "It should not be interpreted any differently."

However, McConnell has talked repeatedly about his support for NATO in the wake of Trump's criticism of it. Support for the alliance has been an issue that has united both parties in the House and Senate.

In January, the House passed the NATO Support Act, which states that it's US policy to remain a member of NATO and prohibits funds from being used to withdraw from the alliance.

Last year, the Republican-led Senate approved a motion of support for NATO the same day that Trump arrived in Brussels, Belgium, for a NATO summit and a bipartisan group of senators introduced a bill that would require Senate approval for the US to withdraw from NATO.

Two senior diplomats of US allies told CNN they found it intriguing that McConnell was willing to do this without first discussing with the White House the optics of Stoltenberg's visit.

The senior Democratic aide also raised the point that a NATO secretary general's address to Congress was not proposed during the Obama administration, saying, "It was not seen as necessary."

The possibility of Stoltenberg's visit was raised during Pelosi's trips in February to the Munich Security Conference and to NATO headquarters in Brussels, the aide told CNN. But the hopes of hosting Stoltenberg have been discussed for a while and "there was widespread interest on both sides of the aisle," the aide said.

Congressional leaders held a meeting to discuss a visit by the secretary general and both Democrats and Republicans came wanting to do it, according to the aide. Pelosi finally extended the invitation to Stoltenberg last month

"There's no way around it. People see this as big. These kinds of visits are rare," the aide told CNN.

Asked Tuesday if he was indeed considering pulling the US out of NATO, Trump replied, "People are paying and I'm very happy with the fact that they're paying."