Washington (CNN) A growing number of Republicans are openly scoffing at President Donald Trump's handling of national security issues, with the Senate's number two Republican bashing Trump's criticism on Wednesday of the heads of the US intelligence community ahead of a vote on a measure disapproving Trump's Middle East policy.

The rebuke from Sen. John Thune of South Dakota, the Senate majority whip, came as the GOP-led chamber prepared to vote on an amendment breaking with Trump's plans to pull the US military away from Syria and Afghanistan.

"I don't know how many times you can say this, but I prefer the President would stay off Twitter -- particularly with regard to these important national security issues where you've got people who are experts and have the background and are professionals," Thune said. "I think in those cases when it comes to their judgment, take into consideration what they're saying. ... I think we need to trust their judgment."

Director of National Intelligence Dan Coats and other top intelligence officials had appeared before the Senate Intelligence Committee on Tuesday and contradicted Trump on a range of issues, including North Korea, Iran and ISIS.

Trump issued a string of tweets Wednesday morning in response, defending his foreign policy decisions and taking issue with their statements, saying in regard to Iran that the intelligence officials were "extremely passive and naive."

The same day Trump's intelligence appointees appeared before the Senate, Senate Majority Leader Mitch McConnell announced an amendment rebuking the President's push to withdraw troops from the Middle East.

"It would recognize the dangers of a precipitous withdrawal from either conflict and highlight the need for diplomatic engagement and political solutions to the underlying conflicts in Syria and Afghanistan," the Kentucky Republican said Tuesday.

Asked about the amendment, Thune said, "I think it reflects ... that we want to trust our military leaders when it comes to some of these decisions."

GOP-Trump break on Syria amendment

A day before the Senate has a key vote on the Syria amendment, McConnell went to the floor to blast unnamed Democrats for filibustering the measure.

"I didn't expect that my colleagues across the aisle would make a partisan stand and try to block this straightforward sense of the Senate amendment, when it really just restates what most of us thought was a broad, bipartisan consensus about American leadership in the world," McConnell said.

But his attack on Democrats couldn't mask the reality summed up in his own complaint: that the Republican-led Senate was set to vote Thursday on a measure authored by the GOP leader himself that would criticize Trump's decision to pull out of Syria against the advice of his military and national security advisers.

"I intend to support it. I think most Republicans will," Thune said. "It reflects the widely held view in the conference that, again, you want to trust our military leaders when it comes to some of these decisions, and obviously these precipitous withdrawals in the past have not been good for us."

Asked why Republicans couldn't persuade Trump in private to reverse his decision instead of turning to a public rebuke via a major vote in the Senate. Thune said, "I think they tried."

"I think a number of our members, as you know, talk to the President on a fairly regular basis and have articulated to him that they think the policies that he wants to employ with regard to Syria, for example, are not the right ones. That's being conveyed," Thune said.

Senate Armed Services Chairman James Inhofe, an Oklahoma Republican, said he will vote for the measure because he thinks it will help clarify that the withdrawal of US troops from Syria should be condition-based.

"He was kind of painted in a corner," Inhofe said of the President. "It was just pull out, walk out. We all saw that the day that he said it. I happened to be with him at that time. And he has always felt it should be condition-based and I think this will clarify that. I think so."

Inhofe was asked if Republican senators felt like they need to be on the record urging Trump not to pull the troops.

"Apparently so," Inhofe replied.

Another Republican senator said Trump's move to withdraw troops quickly had "kicked off an important debate."

"The precipitous withdrawal in Iraq didn't work" said Sen. Rob Portman, an Ohio Republican. "We don't want to repeat that. So, the question is, how do you do it in a careful, thoughtful way working with our regional allies."

It was not clear how many Democrats would oppose McConnell's amendment, even though many of them generally support getting troops out of Afghanistan and Syria.

"My complaint, and I think I speak for a lot of Democrats, we're not against a plan to withdraw US military presence, but it's got to be done in consultation, conjunction and coordination with our allies. You don't just announce it," said Sen. Ben Cardin, a Maryland Democrat who's a senior member of the Foreign Relations Committee.

Sen. Bernie Sanders, a Vermont independent who caucuses with the Democrats, said he couldn't say how he would vote until he studied the amendment.

"I will take a look at it," Sanders said. "I really can't speak to it until I study it."

Sen. Jon Tester, a Montana Democrat, said he would vote for the amendment, if a reporter's description of it held true after the senator had studied it.

"I do think we need to learn from past mistakes and I do think we need to have a thoughtful withdrawal," Tester said. "I think we do agree with the President that the quicker we can get out of Syria the better, but it has to be with a plan, and if it is not with a plan than it would be a huge mistake."

One GOP senator, speaking only on the condition of anonymity, said he expected a "substantial number of Democrats" to vote for McConnell's amendment.

"The reason is, partly because they agree with him on the policy, which is true with some of the more hawkish members," the Republican said. "The second reason is that they would view it as opposite of where the President is. That seems to be part of their MO."