At the height of California's harvest, during a critical farm labor shortage, Sen. Dianne Feinstein, D-Calif., has asked immigration officials to stop cracking down on undocumented field workers, saying she is concerned that it could lead to financial losses and higher food prices. Feinstein, a senior member of the Senate Judiciary Committee, urged Immigration and Customs Enforcement to focus its prosecutions on violent criminals instead of agricultural employers and their workers. "Many farmers and growers in California informed me that their business and livelihood are at risk due to a shortage of legal harvesters, pickers, pruners, packers and farm workers," Feinstein wrote in a Sept. 3 letter to Janet Napolitano, the outgoing secretary of Homeland Security. [...] farmers say the stringent background checks - including E-Verify, an Internet database that checks whether a worker is legal - tougher immigration restrictions, border violence and a weakened job market in the United States have stopped many seasonal workers from making the trek from Mexico. Driving up prices"Because the reality is that the majority of farm workers in the U.S. are foreign-born and unauthorized - which is well known - I am afraid that this aggressive worksite enforcement strategy will deprive the agricultural sector of most of its workforce and cause farmers and related industries across the country significant economic harm, as well as driving up food prices for consumers," the senator wrote.