One of America’s top sheriffs and supporter of President Trump is warning that if the administration doesn’t curb the explosion of illegal immigration across the southern border, the president will lose reelection in 2020.

“This last election was a mandate,” said Frederick County, Md., Sheriff Chuck Jenkins. “If he doesn’t accomplish something, he’s done. His whole campaign was 75% was based on that,” he told Secrets at an immigration roundtable in neighboring Virginia Wednesday night.

Jenkins, a forceful advocate for Trump and against illegal immigration, was in Culpeper, Va., to talk up that county’s bid to work with Immigration and Customs Enforcement.

This is my message to end open borders, America's greatest threat. Stand with many of America's Sheriff's to protect our counties and all Americans. #EndTheBorderCrisis now. pic.twitter.com/5jIBr8vjUF — Sheriff ChuckJenkins (@1ChuckJenkins) April 23, 2019

He warned that the accomplishments so far to limit illegal immigration would be killed if Trump loses to any of the two dozen Democrats running for the nomination, most of whom support loosening restrictions.

“It will undo everything that we’ve managed to accomplish in the past couple of years which is not a hell of a lot but it will just undo it all,” said Jenkins, dubbed “the next Joe Arpaio” for his toughness on illegal immigration that was ripping his county until he led a crackdown.

The administration has been working overtime to solve the crisis and the president knows that his supporters expect success. Trump has promised to announce a new initiative this week.

Jenkins ripped Washington’s muddling on the issue, which he said could be solved if police would be allowed to enforce current law.

“Washington right now is a failure. The president gets it. He understands us. But Congress is afraid to do anything because they want to push the ball down to the next election all the time and make it another election issue,” he said.

[Also read: Pelosi uses Melania Trump's family to slam president's immigration plan]

Supreme Court hands Trump a victory in immigration battle | “The court's conservative justices sided with the Trump administration, which argued as the Obama administration did, against hearings for those convicted of crimes and affected by the law.“ https://t.co/CABQDQOfBW — Scott Jenkins (@ScottHJenkins) March 19, 2019

Fellow Culpeper County Va., Sheriff Scott H. Jenkins said he believes voters will see that Trump is being thwarted by Congress on reforming immigration, and urged the president to keep up the fight.

But like his fellow sheriff from Maryland, he fears the fallout from a Trump defeat in 2020.

“I would say that if he loses, we would continue back on the downward spiral that we were on when the Obama administration left office and it’s a sad direction for the country and one I pray we don’t see,” said Culpeper County Sheriff Jenkins.