Newly filed campaign finance reports show that Republican senators moved quickly last month to boost the 2010 Senate campaign of Rep. Michael N. Castle (R-Del.), one of the party’s strongest candidates to capture a Democratic-held seat.

Eager to increase their ranks beyond 40 seats, several GOP senators donated to Castle through their leadership political action committees, according to reports the organizations filed before a deadline today.

Among those senators who reported giving to Castle in October were Thad Cochran (Miss.), whose Senate Victory Fund PAC gave $10,000; Orrin G. Hatch (Utah), whose OrrinPAC donated $5,000; Pat Roberts (Kan.), whose Preserving America’s Traditions PAC gave $5,000; and Mike Johanns (Neb.), whose Prairieland PAC donated $2,000.