Rep. Mike Castle (R) didn’t raise much money in this year’s third quarter, but he has a lot left in his campaign account to use for his just-announced Senate race.

For the months of July, August and September, when he was weighing his political options, Castle reported raising about $58,000, almost all of it from political action committees and almost nothing from individual donors.

Yet Castle began October with $853,000 in cash on hand, which will give him a nice head start for the race in a state where statewide campaigns are not prohibitively expensive.

Castle is expected to face Delaware Attorney General Beau Biden (D) in the November 2010 election, which will determine who will fill the remaining four years of Vice President Joseph Biden’s term. Sen. Ted Kaufman (D), who was appointed to succeed Biden, is not seeking a full term.