Booker compares gun control fight to civil rights movement; endorses 'Medicare for all who want it' Booker is optimistic about his comprehensive gun control proposal's chances.

Presidential candidate Sen. Cory Booker is optimistic about his comprehensive gun control proposal's chances of success despite the partisan pushback it received in the week following its release, and compared to the potential battle over its implementation to the civil rights movement in an interview on "This Week" that aired Sunday.

"People thought [civil rights legislation] was impossible, but they changed the terms of the debate by expanding the moral imagination of this country," Booker, D-N.J., told ABC News Chief White House Correspondent Jonathan Karl, just prior to becoming the first member of the 21-candidate Democratic primary field to open a campaign office in South Carolina.

On Monday, Booker announced his sweeping gun control plan, which includes calls for universal background checks, an assault weapon ban, a safety training program and mandatory gun licensing and registration. The proposals were swiftly met with resistance from Republicans, but the New Jersey senator said Saturday, just days after school shootings in Colorado and Georgia, that he could not continue to stand by as gun violence became "normalized."

"In my short time on this planet, 50 years, we've had more people killed by gun violence than every single war combined from the Revolutionary War through World War I, World War II, Vietnam," he said. "And what have we done? Massacre in the synagogue. We do nothing. Massacre here in South Carolina in a church. We do nothing. Massacre in my mom’s city of Las Vegas. We do nothing."

The gun violence prevention proposal joins criminal justice reform -- an issue Booker has led bipartisan efforts to address in the Senate -- as the centerpieces of the former Newark, New Jersey, mayor's presidential campaign, which has thus far found itself firmly in the middle of the expansive pack, based on the latest polling.

On health care, an issue where several leading presidential candidates have begun to differentiate themselves, Booker attempted to reconcile his co-sponsorship of Sen. Bernie Sanders' Medicare-for-all bill with his stance that the private insurance industry should not be eliminated -- something called for by both the legislation and a number of the Democratic primary's biggest names, including Sanders and Sen. Kamala Harris, D-Calif.

"The first thing I'm going to do is to dramatically lower costs for Americans, and expand insurance," the senator said.

"I want to be pushing on a pathway towards getting to everyone having coverage and part of that is going to be Medicare for all who want it."

Karl pressed, "Medicare for all who want it is not 'Medicare-for-all,' its Medicare, that's called the public option. It’s not for all."

Booker responded, "Again, as I’m telling you, I have a clear goal in mind that I share with all Americans, health care a right. I think the best way to get there is Medicare for all. I'm also a realist. As a former mayor who got things done who knows that you can't hold progress hostage for some purity."

Despite his relative distance from the top of the field in early polls, Booker noted that "historically, the front-runners at this far out are often not the people that end up winning … early primaries," and refuted criticism that his message of unity and common ground isn't resonating with Democratic voters.

"To be strong, you don't have to be mean. To be tough, you don't have to be cruel," he told "This Week." "We have a common pain in this country, but we've got to get back to a sense of common purpose. And so I can't campaign in a divisive way. I would say you can't campaign wrong and think you're going to govern right."

In April, the chairman of the Polk County, Iowa Democrats summarized some of the criticisms of Booker's outlook, explaining that Booker's message was "compelling," but "the Democratic base is angry as hell" and its primary voters "want to fight," according to Politico.

In South Carolina, reacting to such a notion, Booker recalled a town hall during which a supporter told him he wants to see the senator "punch Trump in the face."

"I just smiled and said, 'Hey man, that's a felony, and us black guys, we don't get away with that that often,'" Booker joked. "The reality is Trump wants us to fight him on his turf and his term. He wants to pull our party down. We will not succeed by showing the worst of who we are, but [rather by showing] the best of who we are."

And as he did with gun control, the senator again invoked the activists of the civil rights movement and their strategy of nonviolent resistance, including against one of the most notorious opponents of desegregation.

"We're here at South Carolina, [at] a historically black ... university, where some of the greatest strength was shown through the civil rights activism where people didn’t raise a fist," Booker said. "We didn't beat Bull Connor by bringing bigger dogs and more powerful hoses."

"You beat demagogues by expanding the moral imagination of the country, bringing people together to overcome them," he added.