What to know about Iowa's primaries as Democrats try to mount a comeback

Iowa voters head to the polls Tuesday for primary elections that have become one of Democrats’ key focuses in their bid to claw back power in a state that once helped launch former President Barack Obama to the White House but has since become a Republican stronghold.

While Republicans still hold an advantage in Iowa, Democrats see openings in a competitive governor’s race, an open Senate seat, and two battleground congressional districts that could help determine control of Congress next year.