PALM BEACH, Fla. — President Trump, blaming Democrats and the Mexican government for an increasingly “dangerous” flow of illegal immigrants, unleashed a series of fiery tweets on Sunday in which he vowed “NO MORE DACA DEAL” and threatened to walk away from the North American Free Trade Agreement.

Minutes after wishing the nation a happy Easter Sunday, Mr. Trump denounced “liberal” laws that he said were preventing Border Patrol agents from doing their jobs. He said that Republicans should use the “nuclear option” to sidestep Democratic opposition in the Senate and enact “tough laws NOW.”

It was unclear whether the president’s tweets represented any change in his immigration policy, or were just the sort of venting he is known to do after reading a newspaper article or seeing a television program. The president, who spent much of his holiday weekend golfing with supporters and watching television, was apparently reacting to a “Fox and Friends” segment on immigration that had aired minutes before.

Whatever his intention, Mr. Trump’s Twitter outburst captured the fickle tendencies that have driven his policy positions on immigration. On one hand, he has suggested at times that he is open to extending citizenship to millions of undocumented people. On the other hand, he has denounced those who have entered the country illegally as brutal criminals and raged about lax enforcement that he said had allowed immigrants to pour into the country.