WASHINGTON—The White House sent Congress an expansive set of principles that would sharply increase immigration enforcement at the border and inside the U.S. and significantly cut the number of new legal arrivals, demanding a high price for legislation under consideration to help “Dreamers.”

The documents arrive as lawmakers begin an emotional and contentious debate over whether to legalize young people brought to the U.S. illegally as children, often called Dreamers. These young migrants will lose work permits and protection from deportation starting in March under a six-month phaseout ordered by President Donald Trump.

The White House documents, sent to congressional leaders in both parties on Sunday, amount to a lengthy wish list of longstanding conservative immigration goals. White House officials told reporters that they want these to be included in any immigration deal, but stopped short of saying the White House will insist on them.

“Without these reforms, illegal immigration and chain migration, which severely and unfairly burden American workers and taxpayers, will continue without end,” Mr. Trump said in a letter to congressional leaders that outlined some 70 separate principles.

Many of these measures are nonstarters for Democrats and some Republicans and insisting on them could put the congressional effort to legalize the young immigrants into jeopardy. A White House official said the president isn’t issuing any veto threats but declined to detail which of the ideas were the highest priority, saying the administration didn’t care to negotiate with itself.