President Trump let loose on Mexico and congressional Democrats in a series of early morning tweets Monday as a caravan of Central American immigrants makes its way largely unfettered through Mexico on its way to the United States’ southern border.

“Mexico has the absolute power not to let these large ‘Caravans’ of people enter their country,” Trump tweeted. “They must stop them at their Northern Border, which they can do because their border laws work, not allow them to pass through into our country, which has no effective border laws.....”

Trump began his Twitter tirade on immigration over the weekend from his home in Florida, where he threatened to pull out of the North American Free Trade Agreement with Mexico unless it does more to stop people from crossing into the U.S. He claimed they're coming to take advantage of protections granted certain immigrants.

“Mexico is doing very little, if not NOTHING, at stopping people from flowing into Mexico through their Southern Border, and then into the U.S.,” the president tweeted. “They laugh at our dumb immigration laws. They must stop the big drug and people flows, or I will stop their cash cow, NAFTA. NEED WALL!”

The president's tweets came after Fox News' "Fox & Friends" reported early Sunday on what it said is a group of 1,200 immigrants, mostly from Honduras, headed to the U.S. The segment was a follow-up to a report by Buzzfeed News on hundreds of Central Americans making their way through Mexico in hopes that American authorities will grant them asylum or be absent when they attempt to cross the border.

“Mexico has got to help us at the border," Trump told reporters before he and first lady Melania Trump attended Easter services at an Episcopal church near his Palm Beach home on Sunday. "If they're not going to help us at the border, it's a very sad thing between our two countries."

"A lot of people are coming in because they want to take advantage of DACA," he added, although it was not immediately clear what Trump was referring to when he said people are coming to take advantage of the program.

Former President Barack Obama created the Deferred Action for Childhood Arrivals program to provide temporary protection and work permits to hundreds of thousands of immigrants who are living in the U.S. illegally after being brought here as children. Trump ended the program last year, but gave Congress six months to pass legislation enshrining it. A deal has so far proved elusive and Trump has blamed Democrats.

“DACA is dead because the Democrats didn’t care or act, and now everyone wants to get onto the DACA bandwagon... No longer works,” Trump tweeted Monday morning. “Must build Wall and secure our borders with proper Border legislation. Democrats want No Borders, hence drugs and crime!”

Trump promised during the 2016 presidential campaign to build a Southern border wall to stop illegal immigration and drugs from Mexico, but Congress has frustrated him by not moving as quickly as he wants to provide money for construction.

Last month, Congress passed a $1.3 trillion funding package that included $1.6 billion in border wall spending. But much of that money can only be used to repair existing segments, not build new sections. Congress also put restrictions on the types of barriers that can be built.

The president also complained on Twitter that border patrol agents can't do their jobs properly because of "ridiculous liberal (Democrat) laws" that allow people caught for being in the country illegally to be released while they await a hearing before a federal immigration judge.

Trump tweeted that the situation is "Getting more dangerous" and threatened to use a “Nuclear Option if necessary” to stem the flow of immigrants coming into the country.

Trump has previously called for the “nuclear option” – which would require the Senate to change rules to end the filibuster. But Senate Majority Leader Mitch McConnell has dismissed the option in the past, saying Republicans will welcome the filibuster when they return to being the Senate minority.

The White House did not immediately answer questions about Trump’s tweets.

The Associated Press contributed to this report.