President Barack Obama's Democratic Party is expected to lose its majority in the House of Representatives, but may hold on to the Senate. Republicans hope to capitalise on voter discontent with the economy.
Up for election are all 435 House seats, 37 of the 100 seats in the Senate, governorships of 37 of the 50 states and all but four state legislatures. The Republican Party needs to gain 39 House seats to win control of the lower chamber of Congress and to take over the Senate. Opinion polls have regularly predicted that the Republicans will seize the House, but the race for control of the Senate is likely to be tighter.
In addition, voters will decide on some 160 measures on the ballots in 37 states ranging from marijuana legalisation in California to a referendum in Oklahoma on forbidding judges from using Islamic Sharia law in rulings. If Californians decide in favour of legalising marijuana possession for personal use, it will put their state at odds with federal law.
