Cory Booker. Business Insider US Sen. Cory Booker (D-New Jersey) is subtly making the case for why he believes former US Secretary of State Hillary Clinton is a better presidential pick than Sen. Bernie Sanders (I-Vermont).

In an interview with Business Insider on Tuesday, Booker, a Clinton supporter, pointed out that although he respects Sanders, none of their colleagues have endorsed him. In contrast, Clinton has been endorsed by almost every Senate Democrat.

"I have a lot of love for Bernie. I value him as a colleague. I have nothing negative to say about him," Booker said. "But I do know that none of his colleagues in the Senate have endorsed him."

Booker was speaking with Business Insider in order to promote his new book, "United: Thoughts on Finding Common Ground and Advancing the Common Good."

The senator was even less hesitant to highlight where he believes Clinton is a stronger candidate than Sanders. Later in the interview, Booker praised Clinton's financial-regulatory plan and contrasted it favorably with Sanders.

Booker said:

When I look at pragmatic plans on how to reform Wall Street, if you separate the people and their personalities, and you were to put up the detailed plan that Hillary Clinton put forward, and the detailed plan that Bernie Sanders [put forward], ... clearly the plan that Hillary has, to me, is a better plan to reforming Wall Street and creating real incentives.

Tax incentives that don't incentivize jobs going overseas. Tax incentives that don't have people in hedge funds paying less tax rates than their secretaries, but also [that] incentivize the kind of investment we need to create hope and opportunity in cities like mine. So we can draw in investment, development, jobs, and more so that everybody gets to enjoy the abundance of this country."

Booker also warned that while he was troubled by financial excesses, particularly in the mortgage industry, demonizing the industry as a whole could discourage investment in key projects that help alleviate poverty. Much of Sanders' campaign-trail rhetoric is fiercely critical of Wall Street practices.

"I don't want to pick out a pitchfork or a brush and paint a broad brush over an entire industry," Booker said, citing the role financial institutions played in helping him develop a hotel and housing while serving as mayor of Newark, New Jersey.

"I'm going to lead the charge, as I did during the recession, going after the mortgage industry, which was really ravaging my city," he said. "But I'm also going to say that we can't go so far that we can't draw capital into our inner cities, which desperately need to grow."

Booker drew some backlash during the 2012 election, when he panned US President Barack Obama's campaign for its criticism of Republican Mitt Romney's role in the private-equity industry.

Over the past several weeks, Booker has hit the trail numerous times for Clinton in early states, making trips to Iowa, New Hampshire, South Carolina, and Nevada.

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