Divided Republicans pointed fingers and promised to regroup yesterday after a stunning Tea Party upset in Delaware dealt a blow to their hopes of recapturing U.S. Senate control.


Conservative upstart Christine O’Donnell’s defeat of popular nine-term U.S. Rep. Michael Castle in a Senate primary ended the career of one of the last Republican moderates in Congress and set off a round of Democratic celebrations.


The loss by Castle, who had been expected to cruise to victory in the Nov. 2 election, bolstered Democratic efforts to keep the Senate seat long-held by Vice President Joe Biden, and it made it tougher for Republicans to pick up the 10 seats they need for a Senate majority.


Republicans are still expected to turn voter worries about the economy and Obama’s leadership into big gains in November, which could give them control of the House and perhaps even the Senate, once considered a long shot.


The Tea Party platform of limited government, lower spending and opposition to Obama has proven a good match with the public mood this year.