US Senator John Edwards formally ended his pursuit of the Democratic nomination, pledging to “do everything in my power” to help John Kerry win the White House.

Republicans and Democrats battled for control of Congress today in mid-term US elections clouded by terrorism, the threat of war and a shaky economy, with voters marking ballots for governor from Maine to California.

The US is braced for more polling day mayhem this week as technical glitches threaten to turn the crucial mid-term vote into a repeat of the 2000 presidential election fiasco.