By Jennifer De Pinto, Fred Backus, Kabir Khanna and Anthony Salvanto

As President Trump plans to visit California Tuesday to see prototypes for a U.S. - Mexico border wall, the idea of building a border wall continues to be unpopular with most Americans, and sharp partisan splits remain. Most Republicans support it, while most Democrats and independents oppose it. These percentages have held steady over time.

We find partisan divides over whether "sanctuary cities" can refuse to assist federal efforts in detaining or deporting illegal immigrants; President Donald Trump visits California amid legal battles between the Justice Department and the state. Half of Americans – and most Democrats - think cities should be allowed to deal with illegal immigrants as they see fit, while another half of Americans – and most Republicans - think such cities should be forced to comply with federal anti-immigration efforts.

On the broader principle of whether states or the Federal government should have power on immigration laws, partisans not only divide, but have switched places in recent years. Republicans today say the Federal government should have authority, not the states – a notion they rejected when President Barack Obama was in the White House and Arizona was drawing attention for passing its own measures; today most Democrats say the states should have power, having reversed their thinking from 2010.

Get Breaking News Delivered to Your Inbox

This poll was conducted by telephone March 8-11, 2018 among a random sample of 1,223 adults nationwide. Data collection was conducted on behalf of CBS News by SSRS of Glen Mills, PA. Phone numbers were dialed from samples of both standard land-line and cell phones.

The poll employed a random digit dial methodology. For the landline sample, a respondent was randomly selected from all adults in the household. For the cell sample, interviews were conducted with the person who answered the phone.

Interviews were conducted in English and Spanish using live interviewers. The data have been weighted to reflect U.S. Census figures on demographic variables.

The error due to sampling for results based on the entire sample could be plus or minus three percentage points. The error for subgroups may be higher and is available by request. The margin of error includes the effects of standard weighting procedures which enlarge sampling error slightly.

This poll release conforms to the Standards of Disclosure of the National Council on Public Polls.

Poll toplines: