Additionally, various reasons have been expressed as to why Trump's immigration reform plan may fail. California politician Gavin Newsom believes that building a border wall is impractical and unnecessary. According to him, the idea would be hampered, among other challenges, by the mountains, rivers, private and tribal lands along the border (Rosenfeld). Additionally, there were concerns that the wall would not prevent relocation to the United States as immigrants were able to cross despite improved border security. The most important argument made so far against the plan is that the success of the deportation program will cause negative effects on the economy. By deporting millions of people, the nation will lose a significant number of workers, especially farmers. According to Gavin, about 6% of the American workforce is made up of immigrants and sending them home is risky for finances