The campaign's announcement came as the Drudge Report said former Secretary of State Condoleezza Rice has emerged as a front-runner to be the presumptive GOP presidential nominee's running mate, The Hill reported.
"We're getting ready to share some exciting news. Sometime between now and the Republican convention, Mitt will be announcing his choice" for vice president, Romney campaign manager Matt Rhoades said in an e-mail to supporters.
Rice, who was secretary of state for President George W. Bush, said last month "there is no way" she would become Mitt Romney's running mate.
Romney's camp has been tight-lipped about who's on the short-list though speculation has been rampant.
Romney, during a town hall event in Colorado earlier this week, side-stepped a question from the audience, saying, "The person I choose, you will look at and say, 'That person could be president if necessary.'"
The Republican National Convention is Aug. 27-30.