Building a wall along the United States-Mexico border to stop illegal immigration and reducing all illegal and legal immigration to the U.S. is the top priority for Republican voters, a poll finds.

The latest Harvard/Harris Poll reveals that Republicans voters rank building a wall along the southern border as their top priority for what President Trump should be focused on executing.

Currently, only 42 miles of mostly replacement barriers have been built at the U.S.-Mexico border, but hardly any mileage of wall has been built to expand upon existing barriers. Every administration since President George W. Bush has built replacement barriers.

Building a border wall to stop illegal immigration is also the top priority for conservative voters and Trump supporters.

Second to building the wall, Republican voters said they want Trump to focus on reducing all illegal and legal immigration to the U.S. Conservatives and Trump supporters ranked reducing all immigration as their second highest priority as well.

Currently, more than 1.2 million legal immigrants are admitted to the country every year, with foreign-born voters expected to account for one-in-ten U.S. voters in the 2020 election.

.@wwwCISorg Report: U.S. is " on track to import roughly 15 million new foreign-born voters in the next 20 years. Of those new voters … between 7 million and 8 million will be brought to the U.S. through chain migration." https://t.co/LFIv0HPnhg via @BreitbartNews @JxhnBinder — NumbersUSA (@NumbersUSA) January 16, 2018

Nearly 70 percent of all legal immigration to the U.S. comes through the process known as “chain migration,” whereby newly naturalized citizens are allowed to bring an unlimited number of foreign relatives to the country with them. Nearly ten million legal immigrants have been admitted to the country through chain migration in the last decade, alone, and in the next two decades, chain migration is expected to import about eight million new foreign-born voters.

The poll shows the divide between the GOP base and the party establishment’s donor class of billionaires and big business executives. While Republican voters want less immigration, the plutocrat Koch brothers and U.S. Chamber of Commerce push mass amnesty for all illegal aliens as well as an expansion of legal immigration levels to provide corporations with an endless stream of cheaper, foreign workers to compete against working and middle class Americans.

Months ago, Chamber of Commerce President Tom Donahue claimed the country is “out of people” and therefore must import millions more legal immigrants every year to take American jobs.

At stake for the GOP donor class’s support for current legal immigration levels and expanding immigration is Americans’ wages.

Extensive research by economists like George Borjas and analyst Steven Camarota has found that the country’s current mass legal immigration system — wherein 1.2 million mostly low-skilled workers are admitted annually — burdens U.S. taxpayers and America’s working and middle class while redistributing about $500 billion in wealth every year to major employers and newly arrived immigrants.

Borjas has previously called the country’s legal immigration system the “largest anti-poverty program” in the world at the expense of blue-collar Americans and middle-class taxpayers.

Camarota, director of research for the Center for Immigration Studies, has found that every one-percent increase in the immigrant composition of American workers’ occupations reduces their weekly wages by about 0.5 percent. This means the average native-born American worker today has his weekly wages reduced by perhaps 8.5 percent because of current legal immigration levels.

John Binder is a reporter for Breitbart News. Follow him on Twitter at @JxhnBinder.