Top Democrats are declining to comment on staggering new numbers from U.S. Customs and Border Protection that show a record 856 illegal migrants were killed trying to cross the southern border last fiscal year, while Republicans are blaming the Biden administration and vowing action to stop the crisis.

According to CBP data obtained by Fox News, 856 migrants died at the U.S. southern border in fiscal year 2022, which is the highest and deadliest ever on record. There have already been 25 deaths in FY23, which began Oct. 1, according to the data.

The numbers also show there were 227,547 ​migrant encounters in September. That figure is the highest September total in the history of the Department of Homeland Security, and a massive increase over prior Septembers: 192,000 in Sept. 2021; 57,674 in Sept. 2020; and 52,546 in Sept. 2019.

Requests for comment on the new CBP data from the White House, Senate Majority Leader Chuck Schumer, D-N.Y., House Speaker Nancy Pelosi, D-Calif., Senate Homeland Security and Governmental Affairs Committee Chair Gary Peters, D-Mich., and House Homeland Security Committee Chair Bennie Thompson, D-Miss., were not returned Monday.

RECORD 856 MIGRANTS DIE AT SOUTHERN BORDER IN FISCAL YEAR 2022: CBP

The Democrats' silence comes just a few years after their outspoken outrage at former President Trump's administration's hard line immigration policies, including the "zero tolerance" policy for migrants illegally entering the U.S.

In 2018, Pelosi called on Trump to end his administration's "inhumane, barbaric" policy to criminally prosecute any adult who entered the U.S. illegally, which led to children being detained separately from their parents.

"Stop this inhumane, barbaric policy, rescind your actions, take responsibility for it," Pelosi reportedly said in San Diego after touring a detention facility. "This is not about immigration. This is about humanity. It’s about family. It’s about who we are as a country."

EL PASO'S MIGRANT DATA DASHBOARD GIVES GLIMPSE INTO ONGOING MIGRANT SURGE

On the other hand, Republicans are decrying the "shocking" death statistics for illegal migrants, calling Biden's inaction a dereliction of duty.

"While President Biden’s radical policies have opened our southern border to record numbers of illegal immigration, deadly fentanyl, terrorism suspects, and, tragically, a record number of migrant deaths, House Republicans are committed to securing our border by finishing the wall and ending catch-and-release," House Minority Leader Kevin McCarthy, R-Calif., told Fox News Digital.

"The Biden administration just wrapped up a record-breaking year of drugs, death, devastation, and a complete dereliction of duty when it came to securing our nation’s borders. The unprecedented number of migrant deaths at the border is shocking," House Homeland Security Ranking Member John Katko, R-N.Y., added.

"Homeland Security Republicans have sounded the alarm on the humanitarian crisis directly resulting from President Biden’s reckless policies, which have incentivized families and young children to make the dangerous journey to the U.S.-Mexico border," Katko said. "The continued silence from Democrats on this humanitarian crisis is deafening. Democrats should be acting to address the devastation at the border. Republicans are ready with a plan to secure the border, address the pull factors created by the Biden administration, and end this humanitarian crisis on day one of a Republican majority. The American people have had enough and Homeland Republicans are prepared to address the raging fire at our Southwest border."

The CBP numbers also reveal there were 20 known or suspected terrorists arrested at the southern border in September, bringing the fiscal year 2022 total for terror watchlist arrests at the border to 98.

"Even more alarming, 98 individuals on the terror watchlist were apprehended trying to enter the U.S. between ports of entry in the last year," said Senate Homeland Security and Governmental Affairs Ranking Member Rob Portman R-Ohio. "Our adversaries know they can enter our country through our failed border."

"We weren’t in this situation under the last administration or the Obama administration because we had in place policies that worked to stem the flow of unlawful migration," Portman said.

A spokesperson for Senate Minority Leader Mitch McConnell, R-Ky., pointed to the senator's many floor speeches on the topic, blaming Democrats for historic border crossings.

"The last two years have seen law and order deteriorate across our country. Public safety has eroded. Violent crimes like murders and carjackings are breaking records. And our southern border has turned into a turnstile," McConnell said in a September floor speech. "We have seen the violence and chaos firsthand in Kentucky, especially in my hometown of Louisville. But we aren’t alone. This is a nationwide phenomenon on Democrats’ watch."

Fox News' Griff Jenkins, Bill Melugin and Timothy Nerozzi contributed to this report.