Voters are heading to polls across the United States Tuesday to cast their ballots in the midterm elections at a time when Republicans are expected to make major gains against the majority-Democrat Congress.

A man arrives to cast the ballot during the midterm elections at a polling station in the City Hall of San Francisco, the United States, Nov. 2, 2010. (Xinhua/Liu Yilin)
Across the country, polling stations opened early Tuesday morning and will close between 6 p.m. and 9 p.m., and Americans are voting in nearly 500 Congressional races nationwide.

VietNamNet/Xinhuanet