WASHINGTON — A prominent GOP senator says Ash Carter's suggestion of changes to US policies on Afghanistan and Ukraine will matter little if he becomes secretary of defense because the White House will simply ignore him.

"I'm confident that he has no influence whatsoever," Senate Armed Services Committee Chairman John McCain, R-Ariz., told reporters Wednesday during a break in Carter's confirmation hearing.

In written statements to the committee, the former deputy defense secretary replied "Yes" to this SASC question: "If security conditions on the ground in Afghanistan degrade in 2016, would you consider recommending to the president revisions to the size and pace of the drawdown plan announced by the president in order to adequately address those security conditions?"

And during a morning question-and-answer period, Carter told senators he "leans" in favor of sending lethal military equipment to Ukraine in its ongoing standoff with Russia.

Both have been regarded as potential areas where he might differ with Obama administration officials. But McCain doubts Carter, if confirmed by the full Senate, will change their minds.

"All of the decisions are made by three or four people at the White House level," McCain said.

On issues ranging from arming Syrian rebels to detainee policy to Ukraine, "a few or all of his national security leaders recommend it, and he turns them down," said the SASC chairman, who lost the 2008 presidential election to President Barack Obama.

"You see that time after time," McCain said, referring to National Security Adviser Susan Rice and others in the West Wing.

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Carter has relationships with a number of those White House national security officials, something the man he would replace, Chuck Hagel, lacked.

In fact, at the conclusion of a December White House announcement during which Obama introduced him as the nominee, Carter was seen giving Rice a big bear hug

Asked whether those relationships could help Carter influence Obama's national security and foreign policies, McCain replied: "It doesn't matter."

"It's micromanagement from the White House," he said.

McCain told Carter at the hearing's start he fears the nominee faces a substantial challenge in being marginalized, saying his three would-be predecessors have been stymied by "over-centralization of foreign and defense policy."

Carter vowed to be "a stickler for the chain of command."

"I have promised President Obama that if I am confirmed, I will furnish him my most candid strategic advice," Carter told the panel. "I will also ensure that the president receives candid professional military advice. This is not only consonant with the law as written in this very committee, but with good sense, since our military leaders possess wide and deep experience and expertise."

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