In addition, various reasons have been given for the failure of Trump's immigration reform plan. California politician Gavin Newsom believes building a border wall is impractical and unnecessary. This idea, he said, would be hampered by mountains, rivers, private and tribal lands along the border, among other challenges (Rosenfeld). Additionally, some fear that the wall will prevent resettlement to the United States, as immigrants have been able to cross the border despite increased border security. The most important argument made so far against the plan is that the success of the deportation program will have negative effects on the economy. By expelling millions of people, the country will lose a significant number of workers, especially farmers. About 6% of the U.S. workforce is made up of immigrants, Gavin says, and sending them home is financially risky.