So I’m sure all you politics geeks out there have heard by now that Rep. Mike Castle, a Republican, is going to run for the Senate seat in Delaware that became vacant when Sen. Joseph R. Biden, Jr. became Vice President Joe Biden. Sen. Edward E. Kaufman, a Democrat, is keeping the seat warm for now, but no one expects him to stick around.

Although the initial statements from the Democratic Senatorial Campaign Committee play up some of Castle’s more conservative stances, he is generally considered a moderate’s moderate. In fact, after the Dems took over Congress in 2006, Democratic strategist James Carville called Castle a “caucus of one,” since he was one of the few centrist Republicans left standing.

A former governor, Castle has an excellent grasp of K-12 issues. (Not every congressman can think on their feet about in-the-weeds-type issues like national standards.) He also seems to have a good working relationship with Rep. George Miller, D-Calif., the chairman of the House Education and Labor Committee. If he leaves the House, and the committee, before reauthorization of the Elementary and Secondary Education Act is complete, that might lessen the chances that the new version of the ESEA would be bipartisan.

Will education be an issue in next year’s Senate race? Hard to say. Castle’s likely opponent is Biden’s son, Beau Biden, who is Delaware’s attorney general. When it comes to education, Castle’s views aren’t really all that different from the Obama administration’s, at least on sticky issues like merit pay. And it’s hard to see Beau Biden dissing the policies his father (and his father’s boss) support. There just might not be enough of a contrast to generate debate.

If Castle wins, the Obama administration may have one more Republican who would cooperate with it on education issues in the Senate. Castle would probably team up with fellow Republican Sens. Richard Burr of North Carolina and Lamar Alexander of Tennessee ... so at least on school issues, he’d no longer be a caucus of one.