Delaware Republican Rep. Michael N. Castle says he’ll take about a month to make a decision about his 2010 political plans.

Speaking to WDEL radio interviewer Allan Loudell on Monday about his upcoming decision, Castle said: “I have a responsibility, primarily to the Republican Party of Delaware, to make it relatively soon. And relatively means in the next month or so.”

Republican strategists in Delaware and Washington are anxiously awaiting Castle’s decision, which will transform the state’s 2010 political outlook. Castle is seriously considering a bid for the Senate seat formerly by Vice President Joseph R. Biden Jr., and he would be the early favorite even though Delaware is trending Democratic.