ASPEN, Colo. (AP) — Mitt Romney is campaigning in Colorado alongside some the Republican Party’s rising stars. And a few of them are thought to be potential running mates for the presidential candidate.

Romney says he’s looking forward to working with GOP governors like Chris Christie of New Jersey, Nikki Haley of South Carolina and Virginia’s Bob McDonnell.

Those governors and others joined Romney at a rally Thursday in Aspen, where the Republican Governors Association is meeting.

Other attendees include Govs. Bobby Jindal of Louisiana and Susana Martinez of New Mexico.

Romney is expected to announce his running mate any day.

Haley says she’ll fight to get Romney elected. Christie says Romney’s a better leader than President Barack Obama. And McDonnell says Romney is focused on the middle class.