Senate Minority Leader Harry Reid (D-NV) on Tuesday called on Republicans to renounce their support for Donald Trump, saying he exploited this weekend’s mass shooting at a gay nightclub in Orlando as an excuse to foment hatred towards immigrants and Muslim Americans.

“Donald Trump proved that he is a terrible leader, as he is a terrible businessman,” Reid said in an address from the Senate floor. “Trump proved he is not the person to lead our nation through difficult times, or in fact any time. Trump failed the most important of tests for a presidential candidate: How to respond in a crisis when our citizens are under attack.”

In a speech Monday laying out his response to the Orlando shooting, Trump reiterated his call for a ban on Muslim immigrants and charged that “political correctness” was crippling the US response to potential terrorist attacks. The presumptive GOP nominee also suggested that President Barack Obama may be cooperating with jihadi extremists, telling Fox News, “There’s something going on.” In the same Fox interview, Trump alleged that American Muslims are aware of potential terrorists in their communities but are either afraid or unwilling to come forward.

“How do you look your son or daughter in the eye and explain that a man running for president is telling your classmates to be suspicious of you, to doubt your loyalty to this country based upon your religion?” Reid asked. “Solely on your religion, purely on your religion. You can’t explain it. I can’t explain it. It’s not possible to explain.”

“Because this level of hate is not comprehensible,” he went on. “It’s incomprehensible that any presidential nominee would foster and promote systematic bigotry, as Trump often does. It’s reprehensible and un-American for the nominee of any major party or any party to declare millions of Americans guilty until proven innocent based on their religion.”

The Nevada Democrat warned that Trump’s rhetoric could encourage physical or verbal attacks against the 3.3 million Muslims living in the United States. Since the 2016 presidential race began, dozens of hate crimes against Muslim Americans have been reported.

Warning that congressional Republicans must distance themselves from Trump or risk “normalizing hatred,” Reid called on Senate Majority Leader Mitch McConnell (R-KY) and other GOP leaders to renounce their endorsements of their candidate.

“Republicans must do what they haven’t had the courage to do,” he said. “Stand up to Trump and say no more.”

Editor’s note: This post originally identified Reid as a “Kentucky Democrat,” not one from Nevada.