There are hundreds of thousands of immigrants in the United States who have been living in the country illegally for years, working and making a living, starting families and sending their children to school. President Biden says they can stay.

And then there are the more recent arrivals, who have crossed the U.S.-Mexico border in record numbers, seeking protection from poverty and persecution. They will have to wait.

Mr. Biden has taken two major actions on immigration this month, expanding legal protections for undocumented spouses of American citizens while also sealing the border to most people seeking asylum in the United States.

Taken together, the decisions put Mr. Biden’s approach to one of the most polarizing issues of the 2024 campaign into sharp focus: He will help immigrants who are already here, but try to keep the border shut to those trying to get in.

The strategy, described by one former White House official as a “border-in vs. border-out” approach, is a reflection of the political complexity of immigration, a top concern for voters of both parties in the 2024 presidential campaign. Polls show that American voters see the situation at the southern border as a problem and that more tend to trust former President Donald J. Trump to handle it than trust Mr. Biden.

Democrats hope that Mr. Biden’s actions this month will help neutralize the issue. Matt A. Barreto, a Biden campaign pollster focusing on Latino politics, said Americans draw a distinction between “long term, undocumented immigrants” and “new arrivals.”