Charleston, South Carolina (CNN) Sen. Cory Booker on Wednesday urged love and legislation to counter a rising tide of hate and gun violence in America, warning in an impassioned speech that "the future of the country hangs in the balance."

"There is no neutrality in this fight," Booker said. "You are either an agent of justice or you are contributing to the problem."

The Democratic presidential candidate delivered his message from a hallowed patch of ground: the Emanuel African Methodist Episcopal Church , the site of a 2015 massacre that left nine African Americans dead. The shooter in that event, Dylann Roof, was convicted of federal hate crimes in 2016.

As the nation mourns two more mass shootings in recent days in Dayton, Ohio, and El Paso, Texas -- the latter motivated by white supremacist ideology -- Booker said the country "must step outside our comfort zones and confront ourselves, to ask the hard questions and genuinely seek answers."

Booker's speech comes as the issues of gun violence and racism have been thrust to the center of the 2020 presidential race, with President Donald Trump set to visit Dayton and El Paso on Wednesday, even as some local leaders have urged him to stay home, including former Rep. Beto O'Rourke, who hails from the border city. Former Vice President Joe Biden is set to deliver a speech on gun violence Wednesday afternoon.

"We need to be honest: about not just who we are, but who we have been," Booker said. He decried "weaponizing hatred...as a political strategy," noting, "These acts of hatred do not happen in a vacuum."

"They are harvested only once they have been planted. ...You reap what you sow," he said. And, in the only direct mention of Trump, Booker added, "It was sowed by a President who spews hateful rhetoric and endangers the lives of people of color and immigrants in this country."

In his remarks Wednesday, Booker renewed his calls for action to reform gun laws in America, an issue that he has put at the fore of his presidential campaign — including a proposal for national licensing of firearms, similar to drivers licenses for cars.

"We have the power to act," Booker said. "And we can act to legislate safety even if we cannot legislate love."

Although Booker did not say Trump's name Wednesday, the implication was clear — and the contrast was stark. As Booker spoke, Trump told reporters he has "concerns about the rise of any group of hate," not singling out white supremacists. And, asked whether his rhetoric has contributed to violence in America, Trump responded, "My rhetoric brings people together."

When Booker finished speaking, his spokesperson Sabrina Singh tweeted, "That was the speech the President couldn't give."

During his speech, Booker stressed, however, that he views this not as "a political moment," but as a defining generational fight. Invoking essayist James Baldwin and Dr. Martin Luther King Jr., Booker called on the country to "dedicate ourselves as our ancestors did to being freedom fighters." And, as he has during other important moments -- including marching in Selma, Alabama, and testifying against Jeff Sessions in the Senate -- Booker wore a black tie, in a nod to the civil rights movement.

"I know I cannot separate the office I seek from who I am," Booker said, "but I am not here today to ask for a vote. I am here today to ask if we again as a nation have the collective resolve to change the reality we live in."