Washington (CNN) Threats against members of Congress continue to climb, Capitol Police Chief Steven Sund said Tuesday, projecting the number of threats this year will "break last year's record."

"We continue to see the threat assessment cases that we're opening continue to grow, for FY 2018, we had approximately 4,894 cases. So far for this year, we have 2,502 cases," Sund said in a hearing Tuesday before the House Administration Committee. "So we're on par to probably break last year's record."

Sund's testimony follows a letter sent Monday by Homeland Security Committee Chairman Bennie Thompson to the chairman of the Capitol Police Board requesting an emergency hearing to re-examine the board's approach to "analyzing the risk environment" for members of Congress. In the letter to Senate Sergeant-at-Arms Michael Stenger, Thompson cited a string of racist tweets from President Donald Trump in recent days aimed at four highly visible Democratic freshman congresswomen of color as his reason for requesting the hearing.

"As you are familiar, inflammatory remarks targeting individuals on social media and in public arena were a central feature of the presidential campaign and now, presidency of Donald J. Trump," Thompson wrote. "The President's rhetoric may insinuate more attacks on Members of Congress."

Trump on Sunday attacked Reps. Alexandria Ocasio-Cortez, Rashida Tlaib, Illhan Omar and Ayanna Pressley on Twitter, saying they should "go back and help fix the totally broken and crime infested places from which they came."

He continued later Sunday, tweeting, "If the Democrat Party wants to continue to condone such disgraceful behavior, then we look even more forward to seeing you at the ballot box in 2020!"

While some members of Congress, including some Republican lawmakers , criticized the President's rhetoric and condemned it as racist, Trump has stood by the attacks, arguing, "I don't have a Racist bone in my body!"

Sund added at Tuesday's hearing that the Capitol Police Board will continue to adjust strategies and emphasize a proactive approach in addressing threats against Congress.

"Our daily reality is that the US Capitol remains a desired target for assailants both domestic and foreign," he said. "Therefore we continually assess the risk and adjust our strategies for addressing any threats."