Americans are about to hold a national election to determine control of the US Congress for the next two years. All 435 seats in the U.S. House of Representatives are at stake, along with one-third of the 100 member U.S. Senate. Republicans hold majorities in both chambers of Congress. If Democrats can win a majority in either chamber, it would become more difficult for President Donald Trump and his Republican party to pass their conservative legislative agenda. Immigration is among the top issues in the midterm camapign. As a way to get his supporters motivated to vote, President Trump is threatening to close the U.S. border as a caravan of migrants makes its way from Central America through Mexico to the U.S. Decisions on updating immigration laws and funding to build Trump's desired border will be made by the next Congress. Also at stake: the fate of 700-thousand working age immigrants who are undocumented, brought to the U.S. by their parents illegally, and raised in America.