U.S. President Barack Obama has beaten his Republican challenger Mitt Romney to win a second term at the White House

U.S. President Barack Obama has beaten his Republican challenger Mitt Romney to win a second term at the White House, TV networks projected Tuesday.

In a tweet to supporters, Obama wrote "This happened because of you. Thank you," as crowds cheered in Chicago headquarters, waiting for him to come out and address his nation.

Obama was projected to have won several key swing states, including Ohio, Pennsylvania, Wisconsin, Iowa, Nevada and New Hampshire, while Romney only won North Carolina. Florida and Virginia.

The battle for the swing states gave Obama at least 290 electoral votes, while Romney just got 201 shortly after midnight.

Obama easily grabbed a host of "deep blue" states including California, Illinois and New Jersey, while Romney prevailed in "deep red" states of Texas, Kentucky and Georgia.

While Obama supporters have already started celebrations of his reelection, Obama himself has yet to make a victory speech.

Meanwhile, Obama's Democratic Party is also projected by CNN to retain control of the Senate while Fox News projected that the Republican Party will hold onto control of the House of Representatives.

In addition to the massive task of tackling 1 trillion-dollar annual deficits and reducing a 16 trillion-dollar national debt, Obama will have to deal with a divided U.S. Congress that is likely to maintain the same partisan makeup in his second term in the White House.

The Election Day began with midnight voting in a pair of small towns in New Hampshire, and expanded across the nation after 5 a.m. (10:00 GMT).Voters lined up from New York to Florida to cast their ballots.