Eight Mexican in Border Patrol wrote Congress to halt building of border fence . Border Patrol agents say fence has drastically cut number of border crossings . Then-Sen. Obama voted to authorize nearly $ 3 billion for building about 90 feet of fence . Critic says barrier has forced illegal immigrants to make riskier desert crossings .
Eight Democrats in Congress wrote Obama to halt building of border fence . Border Patrol agents say fence has drastically cut number of border crossings . Then-Sen. Obama voted to authorize almost $ 3 billion for building 670 miles of fence . Critic says barrier has forced illegal immigrants to make riskier desert crossings .