The Royals have asked permission to interview Astros coach Tony Pena for their managerial job, according to a baseball official. It's believed Royals GM Allard Baird will interview Pena during the Astros' series this week in Philadelphia.

A US Airways reservation agent confirmed that Baird was traveling to Philadelphia on Tuesday, then was scheduled to return to Kansas City on Wednesday afternoon.

The Royals are expected to interview about a half-dozen candidates -- including interim manager John Mizerock and the Royals' triple-A manager, Bucky Dent.

Outside candidates believed to be on the Royals' initial list include Arizona bench coach Bob Melvin, Braves hitting coach Terry Pendleton, Yankees coach Willie Randolph and ESPN analyst Mike MacFarlane.

Other names rumored include ESPN's Buck Showalter and a couple of former longtime Royals players -- Cookie Rojas and Lynn Jones.

Jayson Stark is a senior writer for ESPN.com.