The ideological and tactical contours of Singer’s plans remain somewhat unclear, as does the membership of the American Opportunity Alliance, which is registered as a for-profit corporation in Delaware. If nothing else, though, the group appears to represent a new center of gravity in the world of GOP money, anchored by a famously prolific Republican bundler with a distinct ideological agenda.

Singer, who founded the hedge fund Elliott Management, has long been a key player in GOP money circles, espousing a nontraditional brand of conservatism that includes aggressive backing for gay marriage and immigration reform, as well as more traditional GOP stances like lower taxes and less government regulation. Contributors to the joint fundraising account for Senate candidates — a list that likely dovetails at least partially with the American Opportunity Alliance’s member rolls — include a mix of gay marriage supporters like Todd Ricketts and billionaire investor Cliff Asness, as well as more conventional fiscal conservatives like brokerage titan Charles Schwab and real estate developer Harlan Crow.