Democratic presidential candidate Bernie Sanders says he would do better against Donald Trump in a general election than Hillary Clinton.

“I believe that our campaign is generating the kind of grassroots excitement that will result in a high voter turnout," the Vermont senator told ABC News’ George Stephanopoulos on “Good Morning America” today. "Democrats need a high voter turnout to win. I think we can do that."

Clinton yesterday urged Democrats to consider who would be most likely to win in a general election against the Republicans. “Think hard about the people who are presenting themselves to you, their experience, their qualifications, their positions,” she said. “But particularly for those of us who are Democrats, their electability.”

But Sanders pointed to a recent Quinnipiac University poll that showed Clinton leading Trump by 7 percentage points nationally, 47 vs. 40 percent. But in the same poll, Sanders leads by a broader 13 points, 51 vs. 38 percent. Still, some Democrats think that Bernie Sanders' liberal positions may alienate some independent voters.

When asked whether he would win the Iowa caucuses, he said, "I think we’ve got a real good shot at it."

Recent polling shows Clinton maintaining a slim lead in Iowa.

The comments come hours after North Korea claimed to have tested a hydrogen bomb. "We'll have to lean on China," Sanders said of the U.S. strategy. "China is North Korea's closest ally. They'll have to push North Korea to start adhering to international agreements.

"When you have a hydrogen bomb, if that's true, you are a threat to China, as well," he added.

Sanders also vowed to break up big banks, saying his plan is tougher than Clinton's.

"That's dangerous to our economy and to our political life. We have to break them up," he said. "We have to re-establish Glass-Steagall legislation,” which prohibited commercial banks from participating in the investment banking business. “That is not Secretary Clinton’s position.

"I think what you have is a situation where banks are not only too big to fail, bankers are too big to jail," he added.

Clinton does not support reinstating the Glass-Steagall Act, saying that her plan goes after the “shadow banking” system.

"We are pleased to see that Senator Sanders is finally talking about the importance of dealing with risks posed by activities in the shadow banking system. Unfortunately, however, he failed to put forward a single new proposal that addresses those risks," the Clinton campaign said in response. "We already knew that Senator Sanders wants to break apart financial institutions. What we haven't seen is his plan to deal with the risky shadow banking activities that brought our economy to the brink of collapse in 2008."