WASHINGTON (Reuters) - Republicans in the U.S. Senate on Wednesday re-elected Mitch McConnell to the lead their party, a Senate aide said.

The decision, to be announced later in the day, comes a week after a disappointing election in which Republicans not only failed to win back control of the Senate, but saw President Barack Obama's Democrats increase their caucus margin by two, 55 to 45.

(Reporting By Kim Dixon and Thomas Ferraro; Editing by Doina Chiacu)