As of Monday, Kim, a former California state legislator, was behind Cisneros by only 1.2 percentage points with an estimated approval rating of 49.4 percent. Her chance of winning was relatively lower at 42.5 percent against her rival's 57.5 percent.

Recent opinion polls, including that of The New York Times, found the difference between Kim and Cisneros at 1 point, with 46 percent and 47 percent, respectively.

Election analysts have said such margins are negligible, and could easily be reversed on election day.

Kim has expressed confidence that she will win, particularly with the endorsement of the district's retiring Rep. Ed Royce, whom she worked for as director of community operations.

In New Jersey's 3rd congressional district, Andy Kim is running as the Democratic nominee against incumbent Republican Rep. Tom MacArthur.

The former adviser to former President Barack Obama is leading MacArthur 49.1 percent to 48.5 percent in estimated percentage of vote, and 54.8 percent to 45.2 percent in election probability.

Other polls, including one by The New York Times, have found MacArthur slightly ahead of Kim at 45 percent against 44 percent.

Andy Kim worked as director for Iraq issues on the Obama administration's National Security Council, and enjoys the former president's strong backing.

In Pennsylvania's 5th congressional district, former prosecutor Pearl Kim is the Republican candidate competing against Democratic Mary Gay Scanlon.

She is projected to win 31.3 percent of the vote against her rival's 68.7 percent, dimming her prospects for election.

The only Korean-American to have served in Congress is Jay Kim, a Republican who represented California's 41st district from 1993 to 1999. (Yonhap)