Firing up his drive for health care overhaul, President Barack Obama pressed lawmakers Wednesday to step up to their responsibilities and move legislation this summer, even as his campaign organization rolled out television ads targeting reluctant senators.

A Senate panel cast a milestone vote to advance a bill, the first to act on Obama’s goal. But the party-line decision in the health committee signaled a deepening rift in Congress. While Democrats respond to Obama’s call for action with renewed determination, Republicans are using harsher words to voice their misgivings.