Washington ? The White House signaled Thursday that an aggressive, all-Democratic strategy for overhauling the nation’s health care system remains a serious option, even as President Barack Obama invites Republicans to next week’s televised summit to seek possible compromises.

The administration’s stance could set the stage for a political showdown, with Democrats struggling to enact the president’s top domestic priority and Republicans trying to block what many conservatives see as government overreach.

A senior administration official said Democratic congressional leaders have nearly finished efforts to reconcile two health bills, which the House and Senate passed separately last year with practically no Republican help. Obama will use their legislation to expand coverage to some 30 million and require most Americans to carry insurance as the basis for a proposal that the White House will post online by Monday, three days before the Feb. 25 summit, said the official.