MILWAUKEE (AP) – Republican U.S. Rep. Paul Ryan has added significantly to his campaign stockpile in the last three months, reporting $2.6 million cash on hand.  The House Budget chairman’s July-through-September figures were posted Tuesday. They show his campaign brought in $824,000 during the quarter.  That raises his available reserves to $2.6 million, which represents what’s left after campaign expenses. That’s a formidable total for a congressional candidate, especially in an off-year.  Ryan’s previous Democratic challenger has formed a committee to explore another run. Rob Zerban will hold an “announcement rally” on Oct. 26 but his campaign isn’t saying what the announcement is.  A second Democrat says he’s planning to run. Amar Kaleka has been active in Washington ever since his father was gunned down at their Sikh temple last year.