 -- Vermont Senator Bernie Sanders said today he does not know whether new poll numbers putting him within 7 percentage points of Hillary Clinton in Iowa mean her campaign for the Democratic presidential nomination is in trouble, but his campaign is "doing great."

“You know, it’s not just in Iowa. It’s in New Hampshire. It’s all across this country,” he said on "This Week." "I think people are responding to our message."

Sanders admitted that Clinton was “way ahead" of him in terms of her support among Democratic Party and institutional leaders, but argued that many of them might still support him in the end.

“Democratic leaders are not dumb," said Sanders, the longest-serving independent member of Congress. "What they want and what I want is to make sure that we do not see a Republican gain control over the White House.

“And I think as these look around the country and see the kind of energy and see the kind of huge turnouts we're getting, seeing the kind of young people who, for the first time, are getting involved in the political process ... I think what these leaders -- maybe not today but in a couple months -- will say, 'You know, we want to win.'"

In the Des Moines Register poll released Saturday night, an overwhelming percentage of Sanders' supporters –- 96 percent -- said they support him and his ideas, while just 2 percent said they were supporting him out of opposition to Clinton.

"They want a candidate who is not dependent upon super PACs, a candidate who is prepared to take on and overturn this disastrous Citizens United Supreme Court decision," Sanders said.

When ABC News' Martha Raddatz asked Sanders about the fact that his website does not include any information on foreign policy or a national security agenda, Sanders agreed those were important issues and said his campaign planned to spend more time on them in the future.

When asked specifically about his criteria for the use of force, Sanders, who voted against the first Gulf War, the war in Iraq and the use of force in Syria after the chemical weapons attack in that country, said the United States has too often gone to war unilaterally.

“I believe that the United States should have the strongest military in the world. We should be working with other countries in coalition. And when people threaten the United States or threaten our allies, or commit genocide, the United States, with other countries, should be prepared to act militarily," he said.

“Do we need to go to war in every instance or can we bring pressure of sanctions and international pressure to resolve these conflicts?" he said. "War is a last resort, not the first resort. So you are looking at a guy, yes, there are times when you have to use force. No question about it. But that should be a last resort."

On the question of the use of drones to strike suspected terrorist targets, Sanders said he believed drone attacks had, at times, been effective.

"There are times and places where drone attacks have been effective. There are times and places where they have been absolutely counter-effective and have caused more problems than they have solved. When you kill innocent people, what the end result is that people in the region become anti-American who otherwise would not have been," he said. "So I think we have to use drones very, very selectively and effectively. That has not always been the case."

In 2013, Sanders voted against the CIA Director John Brennan’s nomination in the Senate, citing, in part, the killing of innocent people through the country’s drone program.