Newly filed campaign finance reports show that Republican Senators moved quickly last month to boost the 2010 Senate campaign of Rep. Mike Castle, 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 recently filed reports.

Among those who reported giving to Castle in October were Sens. Thad Cochran (Miss.), whose Senate Victory Fund PAC gave $10,000; Orrin 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.

The donations came just days after Castle announced his Senate candidacy on Oct. 6. His next campaign finance report is due Jan. 31 and will cover receipts and expenditures for October, November and December. Castle had $853,000 in his campaign account as October began.

Castle is likely to face state Attorney General Beau Biden (D) in the open-seat race next year. Biden has not yet revealed his political plans.